Miller was older for his Draft class after spending four seasons at Division III Waynesburg, and he’ll turn 23 shortly after the draft, but he has a big arm and pitched well in 2021 for Gardner-Webb in the Big South.

Mason led the Bulldogs in innings pitched (92.2) and posted a 3.30 ERA over 14 starts, while striking out 121 batters (11.8 K/9) and walking 30 (2.9 BB/9). That walk rate was easily the best of his collegiate career, so there is bound to be some skepticism about whether or not his control has taken a step forward, but it was solid in the spring of 2021.

Miller struggled to gain weight after being diagnosed with Type 1 juvenile diabetes in 2018.  Finding the right treatment and diet in 2020 paid dividends for the right-hander.  (Gallegos - mlb.com - 7/12/2021)

Mason played three seasons at Waynesburg University before transferring to Gardner-Webb in 2020 to play his final season of college ball there.  He graduated from Waynesburg with a degree in finance.

Quotable: “He’s a pro before he’s a pro.  He doesn’t let anything get to him and just goes out there and takes care of business.  He’s also great off the field and in the clubhouse.”  –Gardner-Webb head coach Jim Chester, to The Shelby Star  (Gallegos - mlb.com - 7/12/2021)

July 2021: The A's chose Miller in the third round, out of Gardner-Webb University in NC. And he signed for $599,100, via scout Neil Avent. He was the 97th overall pick; ranked by Baseball America as #236.

Miller went 8-1 with a 3.30 ERA in 15 games, including 14 starts, for Gardner-Webb University to earn Big South All-Conference honors. He led the Big South and ranked 21st in the nation with 121 strikeouts. The 22-year-old right-hander held the opposition to a .210 batting average, which was the best mark in school history. Miller also spent four seasons at Waynesburg and went 18-12 with a 3.92 ERA and 306 strikeouts in 239.0 innings at the collegiate level.

March 7, 2022: On what was the first day of full Minor League camp at Fitch Park in Mesa, Ariz., the A’s hosted a nine-inning scrimmage game against Asian Breeze, a traveling baseball club based out of Arizona.

Mason Miller was among the many A’s prospects who stood out in the 10-1 victory. Taking the mound for the start, Miller showed off a fastball that maxed out at 98 mph as he racked up four strikeouts over two perfect innings. Miller, who finished last season rated as Oakland’s No. 16 prospect per MLB Pipeline, truly carries an inspirational tale into professional baseball. Diagnosed with Type 1 juvenile diabetes in 2018, the right-hander struggled early on in his college career while playing Division III ball at Waynesburg University. Then came his unexpected transformation.

Discovering a new diet and strength program, Miller was able to bulk up his 6-foot-5 frame to around 220 pounds. With that added weight came an uptick in velocity, which played a key factor in his ability to transfer to Division I Gardner-Webb University in time to perform well enough for the A’s to select him in the third round of the 2021 MLB Draft. Entering his first full year with the organization, the expectations are high for the 23-year-old Miller, whose power arm can light up the radar gun as high as 100 mph.

“The arm is real,” A’s director of player development Ed Sprague said of Miller. “He comes at you and throws a bunch of strikes. The question is do you keep him as a starter or fast track him as a reliever and get him to the big leagues inside of a year. He’s just a power, big bodied arm.” (M Gallegos - MLB.com - March 7, 2022)

2022 Season: After sustaining a right scapula strain during spring training, Miller spent most of 2022 rehabbing. When he returned to the mound in August, he leapfrogged his way up the minor league ladder.

He pitched a couple of innings on the complex, skipped Low-A, threw seven High-A innings, skipped Double-A, then closed the season out with two appearances in Las Vegas and a stint in the Fall League.

He blew triple-digits past batters at the top of the zone at every stop, with his fastball averaging 99 mph at Triple-A, and he maintained that upper-90s range in the AFL. So monstrous was Miller’s stuff that he became a lock as an offseason Top 100 prospect, sliding to the back because of his injury history.

Miller pairs the heater with a sharp, mid-80s slider and locates both with consistency. His changeup flashed plus in the Fall League, where he posted a 10.8 K/9 and blew scouts away in live looks. (Tess Taruskin - June 26, 2023)

In 2022, the Baseball America Prospect Handbook rated Miller as the 16th-best A's prospect. But he moved up to #4 in 2023.

But Mason was #1 in the spring of 2024.

2023 Season: Between his triple-digits fastball and devastating slider, Miller, Oakland’s top overall pitching prospect, has all the makings of a frontline starter for years to come. But his immense potential comes with lingering injury concerns that showed through this season with an ulnar collateral ligament sprain in his right elbow that kept him out of action for nearly four months.

Upon returning from injury in September, the A’s were extremely cautious with Miller’s workload, keeping him on a strict limit of 50 pitches over his final six outings of the season. Entering ‘24, the A’s will need to determine whether Miller can hold up as a starter or might be better served as a high-leverage reliever.

April 2024: Mason Miller, OAK, AL Reliever of the Month

Baseball has a new premier flamethrower, and he's taken up residence in Oakland. The A's bullpen has been a pleasant surprise in the early going and Miller played a huge role in their collective breakout. He had a 1.35 ERA in April and struck out 28 of the 51 batters he faced over 13 1/3 IP. He also threw 94 pitches at 100+ mph — by far the most in baseball. (SS Chepuru - MLB.com - May 3, 2024)

Miller grew up a Pirates fan, going to some games at PNC Park. He was asked about any memories.

"My favorite Pirate was Andrew McCutcheon when I was young< Mason recalled. "Jason Kendall was another. My favorite memory was going to a game at PNC for what I think was my 13th birthday (in 2011). We were sitting in right-center field and McCutcheon threw me a warm-up ball in-between one of the innings -- like right to me, so I assume he was trying to throw it to me."

Though Mason grew up a loyal Pirates fan in Pittsburgh, Albert Pujols took precedence as his favorite player. Miller's mother said.

"Yeah, I was kind of a closet Pujols guy because, being a Pirates fan, the Cardinals were in the same division..."

Yes, Pujols will be immortalized in Cooperstown. His legacy, though, goes beyond the Hall of Fame numbers. Pujols is a Hall of Fame person, and that’s really what Miller admires most about him.

In 2005, the first of Pujols’ three MVP seasons, the slugger created the Pujols Family Foundation, which focuses on serving individuals born with Down Syndrome. It’s something that hit close to home for Pujols, whose daughter, Isabella, was born with the genetic disorder.

Miller always remembered how Pujols directed his stardom toward humanitarian efforts. Now that he’s emerged as a star in his own right, the flamethrowing rookie A’s closer is utilizing his platform for a good cause.

Young diabetics finding a champion in A's star closer.

As Miller’s profile has risen throughout the season following a visit to MLB Network and recognition as the American League Reliever of the Month for March/April, families of children with diabetes have reached out to the A’s in hopes of meeting the right-hander. Miller, who was diagnosed with Type 1 juvenile diabetes at 20 years old, was all for it.

During the A’s recent 10-game road trip through Seattle, Houston and Kansas City, the A’s invited a diabetic kid from near the area to a game. Each time, Miller took time during batting practice to meet with each kid and their family on the field.

“I just try to show them I’m a real person,” Miller said. “It’s a cool moment for me as much as it is for them. Being diagnosed at 20, I didn’t really have the same struggles or upbringing that they did. But just being able to be a role model for them is a cool moment for me.”

In Kansas City, 9-year-old Hudson Crutchfield from Oklahoma met his “hero” in Miller on the field at Kauffman Stadium. Miller signed a baseball for Crutchfield, then Crutchfield presented Miller with his own drawing of Miller firing off a 103-mph fastball.

In Houston, Miller met with 8-year-old Shepherd, who was diagnosed with Type 1 diabetes at the age of 6. Miller signed a baseball, took a picture and stuck around for a chat with Shepherd and his father before taking the field for pregame warmups. On his way back to the clubhouse, Miller brought along several other A’s teammates to meet Shepherd.

At T-Mobile Park, Miller met 13-year-old Wyatt from the Portland area. Wyatt is a Type 1 diabetic who is also a baseball player.

“We were able to talk about baseball training, goals and stuff like that,” Miller said. “It’s case to case. Every kid is different. But it’s all a cool experience.”

Before the meeting, Wyatt was private about his diagnosis. After the meeting, Wyatt went public about his Type 1 diabetes on social media.

“That was a cool thing for me to see,” Miller said. “It warms my heart. Everybody has self-image stuff you’re a little more conscious of. I was always a little self-conscious about [my diagnosis] initially because it was different for me. I had no idea what it was, let alone what my friends or people that I would meet would think of it.

“It’s part of who you are, but it’s not who you are entirely. It’s not something you need to be embarrassed about or scared to share. People are going to accept you if they’re good people that should be in your life. People that have an issue with it is not someone you really want to surround yourself with anyway. I talked about that. [Wyatt’s] mom is great and helps him a lot. She just challenged him to take ownership of it. She’s awesome, and it’s great for him to have that support system.”

This is just the beginning for Miller. He plans on expanding his efforts by doing more active outreach in the future and relishes the opportunity to impact the lives of young kids much like he has over the past week.

“It’s a dream for me just to be here playing,” Miller said. “This is a bonus that I’m able to do that for them.” (Martín Gallegos - May 20, 2024)

June 11, 2024: One of the toughest pitchers to square up against: Mason Miller, A's (13% of swings).

We’re already cheating, because Miller has only 168 competitive swings against, and therefore does not qualify for our list. But because he’s been so incredibly good this year, we thought it was worth pointing out here that it’s not just about the 50% (!) strikeout rate. It’s about the fact that even when contact is made, it’s mostly weak, inefficient contact. (Another way to think about this: 87% of the time a hitter swings, he fails to square it up.) (M Petriello - MLB.com - June 11, 2024)

July 2024: Miller was selected to his first MLB All-Star Game.

Sept 18, 2024: Miller induced a 4-6-3 double play in the ninth inning to close out the A’s 5-3 win over the Cubs. The right-hander secured his 27th save of the season, the most by a rookie in Oakland A’s history.

“It’s special,” Miller said. “It’s just trying to get to the next one each time. Now I get an opportunity to kind of look back on the year and the success I've had. It's a special moment that I'm definitely appreciating.” (T Stebbins - MLB.com - Sept 18, 2024)

2024 All-MLB Team Honors - Miller named to the All-MLB Second Team. ( M Gallegos - MLB.com - Nov 14, 2024) 

Sep 3, 2025: In his 12th appearance for his new team, the Padres, reliever Mason Miller threw the second immaculate inning in franchise history. He struck out all three batters in nine pitches, marking the 121st immaculate inning in major-league history. 

TRANSACTIONS

Miller has a 97-102 mph FASTBALL with a 70 grade. The pitch isn’t shaped like the bat-missing, vertically oriented fastballs currently popular. Instead, Miller relies more on its horizontal break and his solid command of the pitch. He gets more strikeouts with his nasty 82-85 mph SLIDER that displays hard 2-plane break, diving out of the strike zone, as a chase pitch and grades 60. He also has a 60 grade 94-97 mph hard CUTTER.

He also has an 84-86 mph 50 grade CHANGEUP. And he has 50 grade control.

When healthy, Mason  flashes a dazzling arsenal that misses plenty of barrels. The righthander has a prototypical starter’s build and a four-seam fastball that averaged 98.3 mph and touched 102 in the majors. The pitch possesses above-average carry and elicits whiffs at the top of the strike zone. Big league hitters batted just .186 against Miller’s heater, and minor leaguers whiffed on the pitch 46% of the time within the strike zone.

They had an even tougher time dealing with his plus slider. The mid-80s offering has sweep and depth, racking up a 47% whiff rate in his truncated big league showing. Mason reintroduced his mid-90s cutter in 2023 after shelving the pitch during his rehab a year prior, using it primarily against lefties. He also sparingly flashes a low-90s changeup. Miller has solid command and throws more than enough strikes to remain in a starting role—that is, if his body holds up. Miller explodes down the mound with force and has a short, quick arm path. His mechanics are fairly sound, but the A’s believe there are some slight biomechanical improvements, such as staying better stacked and on line as he gets down the mound, that he can make to his delivery and finish to marginally aid his durability.

While Miller’s stuff belongs near the front of a rotation, the A’s are debating internally whether he’s better suited for shorter stints given the arm issues. General manager David Forst indicated at the Winter Meetings—at least for 2024—that Miller will likely serve as a reliever. (Mark Chiarelli - BA Prospect Handbook - Spring, 2024)

2023 Season Pitch Usage/Avg. Velo: Fastball 57.4% - 98.7 mph; Slider 22.7% - 86 mph; Cutter 15% - 94.5 mph; Change 5% - 90.7 mph.

2024 Season Pitch Usage/Avg. Velo: 4-seam Fastball 63% 101 mph; Change 2% - 92.5 mph; Slider 34.7% - 87.8 mph.

A power arm who can light up the radar gun at triple digits, Miller also brings what is looking more and more like a wipeout slider. He continues to work on integrating a mid-80s changeup as a third offering, though that pitch still could use some developing.

There’s no question Miller can throw a bunch of strikes with his big arm, and his 6-foot-5, 220-pound frame seems durable enough to hold up as a starter. A quicker path to Oakland, however, could come in a bullpen role as a reliever with all the makings of a flame-throwing closer. Whether he reaches the Majors as a starter or reliever likely hinges on how far he can refine that changeup. (BA - Spring 2023)

Mason has a starter's frame, and his delivery is fairly simple despite a bit of effort, but he'll need to demonstrate he can withstand the rigors of regular rotation turns and maintain his fiery arsenal throughout a full season. 

“I hope we keep him as a starter,” A’s pitching coordinator Gil Patterson said. “This guy’s a beast. With his work ethic, he’s a special guy. Maybe they’ll put him in the bullpen for a year, then they’ll start him. That has worked for a number of pitchers.”

Patterson wanted him to develop his slider and changeup, so he told him not to throw his mid-90s cutter this year.

“He told me, ‘I’m going without my best pitch,’” Patterson said with a laugh. “If everything goes right, we may allow him to bring it back this year.”

There are some evaluators who believe Miller's arsenal could play in a big league bullpen right now. Should the A's remain patient, Miller has the ceiling of at least a No. 3 starter if he harnesses his four-pitch mix and stays healthy. (Mark Chiarelli - Baseball America Prospect Handbook - Spring, 2023/Casey Tefertiller)

Miller is a power arm that can light up the radar gun as high as 100 mph and also holds what at times can show up as a wipeout slider. His mid-80s changeup has shown promise but needs to develop more consistency in order to solidify his pitch arsenal.

Miller has a big league arm that can throw a ton of strikes. The question is what role awaits him. The A’s could choose the long route to build him out as a starter or fast track him in a bullpen role. His big body suggests a starting role could suit him well, even if it means slightly decreased velocity, but that would only come if he can fully develop the changeup as his third pitch. (Spring 2022)

Mason repeats his delivery well and has prototypical size, although he fought his control at times early in his college career at Waynesburg.

While his heater with good velo, doesn't feature a lot of life, Miller displays the ability to locate it to either side of the plate. His slider and changeup show flashes of becoming solid offerings but need more consistency, with his slide piece sharper last fall than it was this spring. 

For a big guy, Miller has good body control and repeats his delivery well enough to reliably provide strikes. He'll need to learn to finish off more advanced hitters, but he has a legitimate chance to start and a nice fallback as a flame-throwing reliever, a reason why he was the second-highest draftee from Gardner-Webb ever. (Spring 2021)

Mason has a solidly built, 6-foot-5, 200-pound frame and throws from a three-quarter arm slot with solid downhill plane thanks to his height and long levers.

2022 Season: A third-round pick by the A’s in the 2021 MLB Draft, Miller missed a majority of the regular season due to a scapula strain but was electric upon his return this summer. The 24-year-old righty’s fastball routinely reached 100 mph in his six Minor League outings as he posted a 3.86 ERA with 25 strikeouts across 14 innings combined between the Arizona Complex League, High-A Lansing and Triple-A Las Vegas. Continuing to build his innings this offseason in the Arizona Fall League, Miller might be on the cusp of a big league callup by next season.  (Martin Gallegos - Oct. 19, 2022)

April 14, 2023: Mason Miller has always been known as a strikeout pitcher.

The No. 3 prospect in the Athletics’ organization, Miller trotted out to the mound already owning a 16 K/9 rate in his Minor League career. That wasn’t enough for the right-hander, though, as he looked like an even different beast for Triple-A Las Vegas in its 14-4 win.

The 24-year-old threw five near-perfect innings, striking out 11 Salt Lake Bees. Only one hitter got on base, and even that came via a strikeout, albeit the dropped third-strike variety.

Even in Miller's one slip-up, he still managed to rack up one more punchout. It was a fitting end for the fireballer, who struck out the side twice. Miller did everything in style with 23 of his 64 pitches registering 100+ mph. Only eight of those missiles went for balls.

"I'm always confident in my fastball," Miller said. "The plan today was to go out and pound it in. Until they hit it, we were going to keep coming with it."

There’s a reason Miller’s fastball grades out as a 70 on the 20-80 scouting scale — it’s the most powerful tool Miller has at his disposal. And when it is working, he is unhittable. Miller is now up to 19 strikeouts in his 8 2/3 innings (two starts) this year. Having yet to register a walk, his fastball is not the only thing driving his success, as his control has also been phenomenal. (E Desal - Pipeline - April 15, 2023)

2023 Season: Miller made three starts between Low A and Double A before again making the jump to Las Vegas to begin the season. He made four starts there where he struck out 23 hitters while tossing 12 scoreless innings. Miller made his major league debut on April 19 and allowed six runs in 8 1⁄3 innings combined in his first two starts. He then tossed seven scoreless innings against the Mariners and allowed two runs over six innings against the Royals before hitting the 15-day injured list with a UCL sprain.

Miller finally returned to action in September, but out of the bullpen with a strict pitch count. He logged 12 more innings across six appearances where he struck out 16 while allowing six runs. Combined, Miller appeared in 10 games and had a 3.78 ERA and a 3.47 FIP to go along with a 27.3% strikeout rate in 33 1⁄3 innings.

What went right? What went wrong?

Miller has shown the ability to be an impact starter at every step of the way during his time as a professional. The fastball velocity is at the top of the charts and he pairs it with a wipeout slider. His changeup is still a work in progress, but he has shown good command if he could only stay healthy. That is really knock on Miller. His delivery has been described as violent and a UCL sprain is a scary situation for any pitcher. (Kris Willis@Kris_Willis - Dec 11, 2023)

April 27, 2024: Mason Miller, pitching in one of the most tense roles in baseball, feels free -- and the radar gun is showing it.

The A's sophomore right-hander, moved to the bullpen in an effort to preserve his health, is suddenly the most electric closer in baseball, blowing MLB's best hitters away with triple-digit heat.

Miller is having a moment. At Yankee Stadium, he mowed down Anthony Volpe, Juan Soto and Aaron Judge to end the game on fastballs that registered at 102.5 mph, 103.3 mph and 102.5 mph. And he got the save.

Miller is 7-for-7 in saves and has a 1.46 ERA in 2024. He has 25 strikeouts in 12 1/3 innings. His fastball is averaging almost 101 mph. (D Adler - MLB.com - April 27, 2024)

May 22, 2024: Miller became the first reliever since 1901 to go 15 games with no runs allowed, 40-plus strikeouts and less than five walks, per the MLB research team.

2024 Improvements: Did you think Mason Miller couldn’t get any nastier on the mound? Think again.

To this point, Miller has established himself as an elite closer by relying on his triple-digit fastball (which has generated a 45.3 percent whiff rate, the highest of any Major League pitcher) and his wipeout slider. His arsenal also includes a changeup, but it’s a distant third pitch as he’s thrown it just twice through his first 20 outings.

Recently, though, the A’s flamethrowing rookie unveiled an interesting new addition to his repertoire.

While closing out a 3-0 win over the Rays on May 28 at Tropicana Field, Miller worked a quick 0-2 count on Brandon Lowe, then he unleashed a pair of pitches that registered at 97.1 and 98.1 mph. They showed up as splitters on the pitch tracker. But these were not splitters, nor were they fastballs.

They were splinkers. You might be familiar with the splinker. It’s a pitch with a split-fingered grip that is thrown as hard as possible and dives down in the zone. Twins closer Jhoan Duran introduced it to the baseball world in 2022. Pirates rookie phenom Paul Skenes also throws a splinker, which is a hybrid between a splitter and a sinker.

Miller had been working on trying to get a feel for the splinker during his bullpen sessions in previous weeks. The three-run lead against Tampa Bay and the favorable count on Lowe gave him enough comfort to finally test it out in-game. Those were the only two splinkers Miller threw, with Lowe taking the first one for a ball before fouling off the second. 

“The first one was the arm-side one,” Miller said. “Just getting to the grip in the game was a little different, so I didn’t really have it in my hand the way I wanted to. Second one was just yanked a little bit, but kind of had the movement I wanted on it. I’m just figuring out how to work that into a game consistently and smartly, too.”  

Miller views his changeup as a solid third offering, but he noted that it does not generate a ton of swing-and-miss. He drew inspiration from watching Duran and Skenes throw the splinker, and he believes integrating his own can make his blazing fastball -- which carries the highest average velocity of any MLB pitcher in 2024 at 100.8 mph -- play up even more.

“I think for at-bats where a guy is fouling off a bunch of pitches or taking some close pitches, it’s just an extra wrinkle,” Miller said. “I’m sure [hitters] will game plan for it a little bit, but obviously you’re going to game plan for my bread and butter, fastball and slider. So if you add another wrinkle, I think that gives you the advantage in an at-bat.”

Asked how good Miller could be if he were to solidify the splitter as a trustworthy third pitch, A’s catcher Shea Langeliers shook his head, almost as if he was in disbelief as he pondered the possibility.

“His fastball and slider combination right now is just so dominant,” Langeliers said. “Adding a third pitch, for me, personally, I don't even know how to go about trying to hit him. He’s a really, really special pitcher. It just seems like he's built for those big moments, both mentally and stuff-wise.”

Miller acknowledged the splinker is still in somewhat of a development phase. Since debuting it, he’s pitched once after that, on Thursday, and did not throw a single splinker among his 32 pitches. For now, Miller plans to continue working on refining it before games and between appearances.“We've talked about how we're going to use it,” Miller said. “It's kind of a work in progress. We'll see. I’ll probably go back to the drawing board on it a little bit.” (Martín Gallegos - June 4, 2024)  

Mason Miller is the best rookie closer in this 2024 class. He made the All-Star team and was as dominant as any pitcher in the game, breaking an All-Star Game record for hardest pitch with a 103.6 mph fastball when facing Trea Turner of the Phillies.

On the season, he has posted a 1.80 ERA with 21 saves in 23 opportunities and 82 strikeouts in 50 innings. He ranks in the 100th percentile in xERA, xBA, fastball velocity, Whiff% and K%. Opposing batters are hitting .137 against his fastball and .116 against his slider. (Bowden - Aug 27, 2024 - The Athletic)

Sept. 18, 2024: His 27th save put Miller into uncharted territory for the club. He is now the sole possessor of the franchise rookie saves leaders after securing tonight’s win, surpassing former great A’s closers (and Rookie of the Year winners) Andrew Bailey (26 saves in 2009) and Huston Street (23 in ‘05)

2024 Season: The 26-year-old flamethrowing right-hander was moved to the bullpen this season to help minimize his injury risk 33and he flourished as the team’s closer, converting 28 saves with a 2.49 ERA, 0.88 WHIP, and 104 strikeouts across 65 innings.

The A's bullpen was highlighted by their 2024 All-Star, Mason Miller, who set the All-Star Game record with the fastest pitch at 103.6 mph. All season, his fastball averaged 100.9 mph, ranking as one of the fastest averages in baseball. Miller finished 2024 with a 2.49 ERA, 104 strikeouts, and 28 saves in 65 innings.

2025 Season: 2025 Traditional Stats: 60 G, 61 2/3 IP, 2.63 ERA, 0.908 WHIP, 1-2, 22 SV, 104 K, 28 BB

2025 Advanced Stats: 162 ERA+, 44.4% K%, 12.0% BB%, 2.56 xERA, 2.23 FIP, 2.27 xFIP, 2.0 fWAR, 2.2 bWAR

 
 Mason Miller enjoyed a strong rookie season, racking up 28 saves and making the All-Star Game while finishing fourth in AL Rookie of the Year voting. Early in 2025, the fireballing righty looked mortal, owning a 6.11 ERA on May 24 after his second blown save in his last three opportunities. However, he began to settle down and lowered his ERA to 3.76 by July 26. With the Athletics out of the race, Miller was traded along with JP Sears to the Padres for a package of prospects headlined by shortstop Leo De Vries, who was ranked the No. 3 prospect in baseball.

While Miller was mostly used as a setup man for Robert Suarez in San Diego, he turned into the most dominant version of himself over the final two months of the season. In 23 1/3 innings as a Padre, Miller allowed just two earned runs (0.77 ERA) and struck out a whopping 54.2% of the batters he faced while holding his opponents to a .096/.205/.137 batting line. In his first taste of postseason action, Miller kept dealing, appearing in two games and striking out eight of the nine batters he faced in 2 2/3 scoreless (and hitless) innings. By the end of the season, Miller’s overall numbers looked almost more dominant than they did in 2024 – his strikeout rate increased from 41.8% to 44.4%, and his opponents’ OPS dropped from .495 to .493. The one concerning area for Miller was his walk rate, which rose from 8.4% to 12.0%.

Miller is the hardest thrower in baseball, with his fastball averaging a blazing 101.2 mph. His fastball generated a strong 37.5% whiff rate, and opponents batted just .163 against it. While Miller’s heater grabs headlines, his slider was his best pitch by a wide margin in 2025, boasting a 54.6% strikeout rate and holding opponents to a .108 average with no extra-base hits. Miller’s slider registered a plus-16 run value, trailing just Chris Sale (who threw more than double the amount of pitches) on the Baseball Savant run value leaderboard. Miller also occasionally mixed in a changeup.

Like Estrada, Miller is 27 years old and has four years of club control remaining. However, he will carry by far the biggest price tag considering what the Padres gave up to acquire him.   (Mathias Altman-Kurosaki | Dec 15, 2025 - Metsmerized)

Miller weighed just 155 pounds and his fastball sat in the mid-to-upper 80s at Division III Waynesburg Univ. in PA. Then doctors discovered he had Type 1 diabetes, explaining his confounding weight loss early in his college career.

April-Aug. 25, 2022: Mason was on the 60-day IL with a right shoulder/rotator cuff strain.

May 9, 2023: A's manager Mark Kotsay said MRI results for Miller's elbow came back "structurally clean." Miller was sent back to Oakland after experiencing tightness in his right elbow following a strong outing in the 5-1 loss against the Royals. 

May 8-Sept 6, 2023: Mason was on the IL with right forearm tightness.

May 16, 2023: After receiving a second opinion from Dr. Keith Meister in Dallas, Texas, Miller was diagnosed with a sprained ulnar collateral ligament in his right elbow. The A’s had originally diagnosed the right-hander with right forearm tightness following his outing on May 7 against the Royals in Kansas City.

Miller remains on the 15-day injured list. (M Gallegos - MLB.com - May 16, 2023)