July 20, 2021: The Mariners drafted and signed RHP Bryan Woo in the 6th round, out of California Polytechnic State University in San Luis Obispo, CA.

Woo fell under the radar in high school but pitched so well in the Alaska League after his senior year that teams tried to sign him as an undrafted free agent. He instead stuck with his commitment to Cal Poly and spent three seasons bouncing between the bullpen and rotation, capped by a breakout junior year that was cut short by Tommy John surgery.

The Mariners drafted Woo in the sixth round in 2021, signed him for $318,200, via scout Chris Horn, and guided him through the rehab process, a decision that paid off when he returned to the mound in 2022. Woo zipped up three levels to High-A, then emerged in the Arizona Fall League with an 0.84 ERA in five starts.

In 2023, the Baseball America Prospect Handbook rated Woo as 7th-best prospect in the Mariners organization.

MLB debut (June 3, 2023): Bryan Woo took a couple of deep breaths, went into his simple delivery, and fired his first official Major League Baseball pitch. The 92-mph fastball was right down the middle of the plate about belt high.

But unlike games in the Class AA Texas League, the get-me-over first pitch wasn’t watched for a called strike.

Marcus Semien, the leadoff hitter of the best offense baseball, jumped on it, sending a double into the left-field corner.

Welcome to The Show, kid.

Woo’s second pitch — a changeup that stayed up in the same area as the first pitch — was ripped into right-center for a run-scoring single by Corey Seager.

The Rangers’ rude welcome to the big leagues would only grow more inhospitable. They scored two more runs off Woo in the first inning and added three more in the second inning, ending his outing much earlier than anticipated.

The Mariners, who had even given Woo a one-run lead before he’d even taken the mound, haven’t been hitting well enough to overcome such an early deficit. And the Rangers, being the Rangers, continued to score runs in what eventually devolved into an embarrassing 16-6 rout with first baseman/designated hitter Mike Ford pitching the eighth inning.

“Just a rough day all around,” manager Scott Servais said. “They jumped on him early. They are a very aggressive team on the fastball, and they got on him.”

After giving up two hits on his first two pitches, Woo came back to strike out Nathaniel Lowe looking for a much needed out. But it didn’t get easier. He issued a four-pitch walk to Adolis Garcia, struck out Josh Jung swinging, and couldn’t finish off switch-hitting catcher Jonah Heim.

Woo got up 0-2, but Heim hammered a couple of pitches into foul territory and took advantage of a 97-mph fastball in the center of the plate for a double that scored both runners for a 3-1 lead. Woo’s third out of the inning came on a swinging strikeout of Mitch Garver.

“The middle ball was in the middle of the plate,” Servais said. “He struggled to really get into any secondary-type pitches with his changeup and breaking ball. It doesn’t matter how hard you throw, you have to stay out of the middle in this league. I think it shows how good Luis Castillo was last night. Because it’s a tough lineup to get through and hold them down.”

The young right-hander had little time in the dugout to exhale and process what just happened. His teammates went down in order against Rangers starter Andrew Heaney to force him back out there in what seemed like less than five minutes.

The second inning didn’t go much better than the first for Woo and the group of 18 people, including his parents and brother, that flew in for his first start.

He allowed a leadoff single to Ezquiel Duran on 1-0 fastball that stayed in the middle of the plate. Semien waited until the third pitch of his second at-bat vs. Woo to take advantage of a hittable fastball for a hard single to put runners on first and second with one out.

Seager showed no such patience. He ripped a first-pitch slider foul and turned on the second pitch, also a slider but in the heart of the plate, for a double down the first-base line that scored both runs. Lowe followed with a single to left to score Seager and make it 6-1.

Woo managed to end the inning with a pair of ground-ball outs. But the damage was done, and so was his outing.  (Ryan Divish - June 2023)

100 SPECIAL FANS

July 3, 2023: The game had been over for nearly an hour and just about all of the ticketed 40,691 viewers had left, even after a fireworks show for the Fourth of July. 

Yet the crowd that awaited Bryan Woo at Oracle Park after he twirled six brilliant innings against the team he grew up rooting for took up a massive portion of the bleachers down the right-field line. When Woo’s mother, Hilary, estimated that more than 100 friends, family and former teammates of his at Alameda High School across the Bay and from Cal Poly State University were in the house, it was not an exaggeration.

“For the last couple days, we've all been looking at each other, like, is this real?” Hilary said from a very crowded concourse. “Is this really happening?”

Most special among that group was Woo’s paternal grandfather, John Woo, who inspired the young pitcher's passion for baseball. John is 93 years old, has Type 1 diabetes and struggles with mobility. But he wheeled himself, quite literally, to the ballpark to see his grandson play baseball for the first time at any level, purchasing a luxury suite for roughly 30 people.  

“He hasn’t been too mobile the last couple of years, so it’s kind of tough for him to travel,” Woo said after the Mariners stormed to a 6-5 win. “He was like, ‘I’m not going to miss this one for the world.’ I’m really glad that he was able to come.” 

Hilary, however, needed to be closer to the action, watching intently from section 107 with a large group of Woo’s childhood friends. 

“I love the game,” she said. “I could sit here and watch three games back-to-back-to-back. I could watch 27 innings and not get bored. I love this game. And so to have my kid competing like this is absolutely one of the best things that you can imagine.”

Her studious acumen turns into awed tension when watching her son. She was in Arlington for his MLB debut on June 3 and again in New York for his impressive performance at Yankee Stadium on June 22. But it didn’t come close to matching the surreal energy in San Francisco, where she and her husband, Clayton, brought Woo to games throughout his childhood. 

“It's more like excitement, but it's also, he's my kid,” Hilary said. “And I want him to do well. And that's the parent thing, and a lot of his friends and family get excited. But as the mom, you know what he's invested in this sport, and you know what he's put into it. And you just, it's pretty simple — you just want them to succeed.”

The sheer volume of Woo’s support system underscored how much that group means to him, and vice versa. Any big leaguer will tell you it took countless people to help them reach this point, and for Woo, it tangibly showed by his crowd. Work ethic and deliberation got him here, too. Woo played virtually all sports as a kid before carving out a more baseball-tailored career path that led to a scholarship at Cal Poly, one of the few schools that offered him one.

And it goes all the way back to Little League. Like most parents, Hilary and Clayton would delegate responsibilities on Woo to ensure that he could prepare himself — from tasks as simple as remembering to pack his uniform and gear, which Woo outlined with a hand-written checklist.

“He even would lay them out on the floor, so that he could get up in the morning and just put them on,” Hilary said. 

It’s evident that guidance has carried into his blossoming MLB career. At only 23 years old and after only six starts, Woo has impressed his teammates and coaches with his preparation and adjustments. Facing a lineup with six lefties in consecutive outings, and having to toy more with secondary pitches, is a prime example. He surrendered just two runs in San Francisco and showed composure in spite of the huge personal moment and pitching in one of the league’s more animated environments. 

“He was really focused all night,” Mariners manager Scott Servais said. “He’s calm, cool and collected. He’s California cool. I’ll go with that. He handled it great tonight.” (D Kramer - MLB.com - July 4, 2023)

July 6, 2025: Woo was selected to the MLB All-Star Game. 

Bryan Woo is as close to automatic as any pitcher on the planet. 

“I’m never trying to fool around,” Woo said on the bench before a game in Philadelphia. “I’m never trying to spot corners and finesse. I’m going right after you. And I feel like if I do that consistently, then it breeds efficiency, and efficiency gets me deeper into games.”

No pitcher in a decade has been as efficient as Woo from the start of a season into late August. He has lasted at least six innings in each of his first 24 starts, becoming the first starter to do that since Zack Greinke in 2015.

Woo’s precision, though, makes him a distinct case in MLB history. According to the Mariners, he is the first pitcher ever to open a season with 24 consecutive starts of at least six innings and no more than two walks. Woo is 10-7 with a 3.02 ERA, striking out 153 and walking 28 across 152 innings.

According to Sports Info Solutions, he throws fastballs (four-seamers or sinkers) 72.4 percent of the time, the most of any qualified pitcher in MLB. Woo, 25, never saw himself as a pitcher in the first place. He wanted to be a shortstop and volunteered to pitch when his high school team needed an arm. The scout was Trent Blank, now the Mariners’ director of pitching strategy, he didn’t scout Woo in person, and he didn’t need to. He saw enough in the arm action and range of motion of an injured, ineffective pitcher to push for the Mariners to take him. 

“Trent’s interpretation, and I’ll translate it roughly this way, was: ‘Through the lens I’m looking through, I would take him (first overall) in the draft — I just think there’s so much potential to help him grow,’” president of baseball operations Jerry Dipoto said. “So we worked something out with his agent; we drafted him in the sixth round, we overpaid him to urge him to sign rather than going back to school or a transfer portal. And he trusted us.”

Woo signed for $318,200 as the 174th pick in the 2021 draft — and so far, he has easily outperformed all the 15 pitchers taken in the first round. The way he throws his fastballs distinguishes Woo from the rest. (Kepner - Aug 22, 2025 - The Athletic) 

Woo can touch upper-90s with his 60 grade FASTBALL. He has a mid-upper 80s SLIDER with a 55 grade. He also has an upper 80s CHANGEUP with a 50 grade. And he has 55 grade control.

Bryan is a 6-foot-2 righthander with an easy, explosive delivery. His plus fastball sits 93-94 mph and touches 96 with above-average ride that helps it miss bats in the strike zone. He primarily pitches east to west with his fastball, but he has the command to elevate it and get chase swings above the zone. Woo complements his fastball with a sweeping, mid-80s slider that he commands to his glove side and plays well against righthanded hitters.

The quality of his slider can be inconsistent, but it generally ranges from average to plus and is consistently competitive. Woo's firm, 87-90 mph changeup has progressed rapidly in a short time and flashes above average with late drop and run away from lefthanders. He is a good athlete who pounds the strike zone with above-average control, though he occasionally gets too much of the plate. His command should sharpen the further he moves away from surgery.

Woo has the ingredients to be a mid-to-back-of-the-rotation starter, but he has to show he can maintain his stuff over a full season. (Kyle Glaser - BA Prospect Handbook - Spring, 2023)

2023 Season Pitch Usage/Avg. Velo: Fastball 49% - 95.2 mph; Sinker 25.7% - 95 mph; Cutter 25% 87.7 mph; Slider 9% - 83 mph; Change 3.5% - 89.7 mph.

2024 Season Pitch Usage/Avg. Velo: 4-seam Fastball - 48% - 95 mph; Sinker 24% - 94.7 mph; Change 8.3% - 89.5 mph; Slider 19.5% 84.5 mph.

2025 Season Pitch Usage/Avg. Velo: 4-seam Fastball 46.7% - 95.7 mph; Sinker 25.6% - 95.3 mph; Change 7% - 89.5 mph; Slider 20.8% - 86.5 mph.

With strong command of his three-pitch mix, Woo posted a 33.6% strikeout rate across 57 innings at Everett, Low-A Modesto and the Arizona Complex League.

Woo then excelled in the Arizona Fall League, where he struck out 16 of 47 batters and allowed only one earned run in 10.2 innings.

“Kudos to both him and our scouting department for getting him where we did,” Mariners assistant general manager Andy McKay said. “He performed at a very high level. 

I really don’t know that his first year could’ve gone much better.”

Woo sports a 93-94 mph fastball with significant ride. He complements it with a sweeping mid-80s slider and a high-80s changeup that has considerable run.

“It’s a three-pitch mix, with all three pitches on any given day being average to slightly above average,” McKay said. “(And) it’s the command of them. It’s just strike after strike after strike.”

The 23-year-old Woo, who primarily was an infielder growing up, benefits from an athletic and polished delivery.

“It really is a beautiful thing to watch,” Everett manager Eric Farris said. “His body moves very well, which allows him to generate good stuff and good power.

“And when you’re able to pair such great action with the ability to locate it, it becomes very hard to hit.” (Cameron Van Til - Baseball America - Feb., 2023)

While the Mariners will build Woo back up slowly post-TJ surgery, he was quickly showing some of the exciting stuff that made him a rising prospect before the injury. He can touch the upper-90s in short stints with his fastball, but while he will flash some ride with good extension on occasion, it’s often too straight and thus, hittable. His hard slider, thrown in the mid-to-upper 80s, has the chance to be an out pitch later in counts and his 87-89 mph changeup flashes plus with big run on it. He is just starting to fold back in a curveball he used in college.

Woo’s strike-throwing had improved over his years at Cal Poly, and he was doing a good job finding the strike zone out of the gate during his debut. The Mariners hope he keeps trending up in that regard, which would give him the chance to start. (Spring 2022)

2022 Season: A sixth-round Draft pick in 2021, Woo didn't make his professional debut until this past June after finishing his rehab from Tommy John surgery. In 57 innings split between the ACL Mariners, Single-A Modesto and High-A Everett, he posted a 4.11 ERA with 84 strikeouts and 22 walks.

2023 hottest pitching prospect in the Mariners: Bryan Woo, RHP (No. 6)

Woo returned from Tommy John surgery last year and his stuff was electric, both late last year and in the Arizona Fall League. He’s showing that it was no fluke in Double-A this season. Over the last month, he’s amassed 27 IP over five starts, posting a 2.00 ERA, a 0.89 WHIP and 34 K’s. He’s currently in the top five of all Texas League pitchers in ERA (2.08), WHIP (0.90), BAA (.181) and strikeouts (53). (Callis, Dykstra & Mayo - MLB.com - May 26, 2023)

After some eye-popping strikeout numbers in the minor leagues, Woo has debuted with 17 2/3 innings and 25 strikeouts in the major leagues, so that part has traveled with him. The Stuff+ model loves his sinker, which hums along at 95 and gets top-20 horizontal movement among righty sinkers by starters. According to Baseball Savant, he’s allowed a .615 slugging (one homer and four singles) when his expected slugging was .316 on the pitch.

Against lefties, he has a more average four-seam fastball by Stuff+, due perhaps to some arm-slot-induced sink, but he throws it exclusively up in the zone and has gotten 18 percent whiffs on the pitch so far. This looks like an enticing duo. Long term, there’s a lot to like here, but in the short term, he may be a pitch short. He hasn’t trusted the changeup, and his slider is a sweeper, which traditionally has poor splits against lefties — who have put three of the 12 they’ve seen into play: good for a single, a double, and a homer.

If Woo comes back with a gyro-slider or a more 12-to-6 curve along with his sweeper, he could really take off. For now, he’s all fastball and not much else against lefties, and that’s a problem. (Sarris - Jun 23, 2023 - The Athletic)

2023 Season: The 24-year-old righty made his MLB debut with the club last season and made 18 starts in the big leagues, pitching to a roughly league average 4.21 ERA with a 4.36 FIP in 87 2/3 innings of work. While Woo paired a solid 25.1% strikeout rate with an 8.4% walk rate, he saw a hefty 13.4% of his fly balls leave the yard for home runs last year.

That proclivity toward the long ball limited Woo’s ability to establish himself as a mid-rotation starter, though even if he were to fail to take a step forward, he’s shown the ability to be a quality back-end arm for a Mariners team loaded with controllable pitching talent.

June 6, 2024: Woo set a Mariners team record for the lowest ERA through the first six starts of a season, having allowed just four runs through 33.2 IP, for an ERA of 1.07.

2024 Season: Woo’s 2.89 ERA in his second season is obviously impressive, but what was even more eye-popping was 101/13 K/BB over his 121 frames. No player avoided walks better than he did with a 2.8 percent rate, but his 4.8 percent barrel rate allowed -- 91st best in the sport -- and well above average hard-hit rate (35.2 percent) shows that he is one of the toughest pitchers to square up as well.

His lack of swing-and-miss stuff makes him a little riskier than some, but Woo offers safety because of his ability to fill the strike zone and limit weak contact. (Christopher Crawford - Oct 21, 2024)

6 INNINGS

That's the longest streak in MLB history to begin a season by a pitcher 30 or younger, tied with Clayton Kershaw in 2016, per OptaStats. (Billy Heyen - The Sporting News)

That ties Randy Johnson's franchise record for consecutive starts of six-plus innings to begin a season. The Big Unit did that back in 1993, according to The Seattle Times.

Aug. 11, 2025: He’s the first pitcher since Clayton Kershaw in 2019 to start the season with 23 straight starts of 6+ innings,” the MLB's social media team posted on X (formerly Twitter).

Aug. 16, 2025: Woo broke a record that had stood for nearly six decades. He became the first pitcher in MLB history to open a season with 24 consecutive starts of at least six innings while issuing no more than two walks, surpassing Hall of Famer Juan Marichal’s 1968 streak. (Abdullah Imran - CLUTCHPOINTS)

2025 Season: Woo has been the top starter. He has made 30 starts this season and 21 have been quality starts. Woo has a 15-7 record along with a 2.94 earned run average. He has struck out 198 batters in 186.2 innings.

Woo went 15–7 with a 2.98 ERA and 198 strikeouts in 186.2 innings, finishing fifth in American League Cy Young voting. He was firmly established as the team's ace and one of the league's best starters when he suffered an injury to his pectoral muscle on September 19, during a start against division rivals, the Houston Astros.

March 2021: Woo suffered an elbow injury that required Tommy John surgery.

But the Mariners still selected the Cal Poly righthander in the sixth round.

Aug 5-22, 2023: Woo was on the IL with right forearm inflammation.

March 26, 2024: Woo started the season on the injured list due to elbow inflammation. An MRI showed no structural damage to Woo’s elbow, but he will be shut down for seven days before beginning to throw again.

“He did not feel good going into his last bullpen, couldn't get loose,” Hollander said. “We cut it very short. Fortunately, [the] MRI, everything else came back very clean structurally. No damage to the UCL ... Just a little mild inflammation.”

April 12-May 10, 2024: Woo opened the season on the 15-day injured list after he couldn’t get loose during his last bullpen session and had to cut it short. He had yet to pitch more than four innings in a start during Spring Training. 

June 25-July 12, 2024: Woo was placed on the 15-day IL with a right hamstring strain.

July 27, 2024: The Mariners' electric righty left after throwing 70 pitches over four innings, which Mariners manager Scott Servais revealed postgame to be related to the right hamstring that landed Woo on the injured list the previous month. Specifically, Servais said that Woo aggravated the area during a 25-pitch third inning.

"He gutted it out and got through the fourth," Servais said. "He didn't have as good as stuff and I knew he wasn't feeling great, and I just decided to pull the plug at that point."

Sept 28, 2025: Woo missed his final scheduled start on Sept. 25 but was not placed on the IL. He began playing light catch on Sept. 25, marking his first significant step toward a potential return for the ALDS. 

Oct 4, 2025:  Woo was left off the club’s 26-man roster for the best-of-five round against the Tigers.