Bryan Woo Sucked in College. Now He’s a Star in MLB | Baseball Bits

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Bryan Woo’s career at Cal Poly of the Big West Conference baseball didn’t exactly go to plan. He struggled with a 6.49 ERA, and never established himself as a starter. Despite this, the Mariners draft Bryan Woo decision has been huge for the franchise. The 2021 MLB Draft featured a lot of early “busts,” but a 6th round pick like Bryan Woo has been great. And that’s because Mariners Trent Blank, director of pitching strategy, advocated for his selection.

Some topics discussed in this video include: Vertical Approach Angle baseball (VAA for short), baseball arm angles and baseball arm slots, and baseball analytics, especially those captured by platforms like Rapsodo baseball, Trackman baseball, and Statcast Hawk-Eye baseball. And all taken into account in the Trent Blank Bryan Woo decision.

I hope not just Seattle Mariners pitching fans or college baseball fans, but fans of all MLB will enjoy this episode of Baseball Bits, a baseball video essay series.

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Adam Jude on Trent Blank: https://www.spokesman.com/stories/2024/jul/13/how-mariners-pitching-pipeline-mines-mlb-draft-for/
Baseball America 2021 Draft rankings: https://www.baseballamerica.com/rankings/2021-mlb-draft-best-available-prospects-remaining/
Ted Williams “The Science of Hitting”: https://www.youtube.com/watch?v=SJ5iiaF-T3I

Soundtrack by William Kage: https://www.williamkage.com

box here’s a healthy dose of perspective at the end of the day pitching is all about run prevention which is why it’s so bizarre that this video is about a pitcher who in his draft year of 2021 was the 73rd best pitcher in his college conference by erra brian Woo’s final collegiate season for the Cal Poly Mustangs of the Big West Conference ended unceremoniously as he underwent Tommy John surgery in April but the draft was coming up that summer and Mariners director of pitching strategy Trent Blank was all aboard the Brian Woo train although he was the number 337 ranked draft prospect according to Baseball America the Mariners drafted him 174th overall in the sixth round why the reach as Blank put it to GM Jerry Dotto I know this is going to sound crazy but this guy would be 1-1 for me if Blank had his way Woo wouldn’t have been a sixthrounder rather the number one overall pick in the entire draft he was that confident in a reliever with a career college erra well over six who just had major elbow surgery and he was right three years after the draft and two years after recovery Woo was a top 10 starter in the big leagues by erra what did Trent Blank and the Mariners see in Brian Woo that nobody else could and how did they see a great MLB starter hiding underneath a bad college reliever [Music] the boring answer to that question would be his strikeout rate and walk rate despite the poor erra Woo had the best strikeout percentage minus walk percentage in the Big West Conference that year a simple metric with the stronger correlation to future erra than past erra alone but of course every big league team knows that already woo had the second highest drafty year erra out of the 19 college pitchers selected in the sixth round in 2021 and contrary to expectation the higher erra hurlers from that round have tended to reach the big leagues more so than the effective run preveners scouting departments are able to use advanced data to divorce good process from bad results at Calpali it started with a Rapoto for bullpens in the fall of 2018 then Trackman in their ballpark by 2020 these systems like Hawkeye Statcast at the big league level use high-speed cameras and radar to track the baseball in flight for pitchers that includes measurements like velocity and movement but even Woo’s fast ball wouldn’t have jumped off the page in that regard in the majors he’s averaged about 15 in of induced vertical break meaning it rises 15 in higher than a theoretical pitch thrown at the same velocity but without any spin the ball doesn’t actually rise but it uses that imparted spin to fight off gravity the best it can this quality is commonly referred to as ride or carry at 15 in of break Woo is actually below the league average for seam fast ball as described in his draft scouting report his velocity was mid90s out of the bullpen and low 90s those rare occasions he actually did start for the sake of comparison the only 2021 sixthrounder with a worse erra Carson Seymour was routinely pumping upper 90s as a starter nowadays Woo averages 95 miles per hour on his four seam and two seam throughout his starts a major uptick that Trent Blank and the Mariners might have been able to project based on video woo’s athletic delivery features excellent hip shoulder separation a hallmark of fireballers throughout the years as the front leg swings open pointing the hip towards the plate the shoulders and chest remain closed pointed towards the dugout eventually they too unccort creating a bodywide rubber band effect a prospect with mediocre velocity but elite hip shoulder separation flashes the potential to throw harder someday but Brian Woo’s standout quality wasn’t how hard he was throwing and it wasn’t how the ball moved either what mattered was where exactly that pitch was coming from [Music] brian Woo releases the baseball approximately 5 feet off the ground 10 in lower than the MLB average pitchers don’t throw from wonky arm angles just for fun they do it to create difficult angles for hitters pitchers are tall people who stand on a hill the average pitcher is 6’3″ throwing from a 10-in high mound and typically releasing the ball at or above head level they’re aiming for a strike zone the middle of which is only two and a half feet off the ground that means the average pitch loses about three and a half feet of elevation during flight it starts high and ends low creating an angle specifically called the vertical approach angle VAA for short in order to mirror the ball’s downward trajectory and maximize contact hitters need to swing with an upward trajectory rather than flat here’s Ted Williams the ideal swing has always been one that was slightly up slightly up the pitcher throwing the ball to the plate into the strike zone is delivering the ball at somewhere from 4 to 8° of angle if you swing in the opposite plane in which the ball is being pitched from your chances of making contact are much greater for a more modern example some of the best pure hitters of today swing with more exaggerated uppercuts than most luis Arise is a prominent example with three batting titles to his name in counting the same could be said about career 300 hitter Freddy Freeman but with batters swinging up to increase the potential area for contact pitchers can create a flatter approach angle to decrease that area the two things they can do are release the ball lower to the ground and aim it higher in the zone with a vertical approach angle of -3.8 degrees Woos for seam creates the flattest angle of any forcing fast ball thrown at least a thousand times since 2023 his flatter approach angle causes him to miss bats despite fastball movement and velocity that in a vacuum wouldn’t otherwise stand out as elite in the pitching world weird often equals good one of the worst things a pitcher can be is too cookie cutter and a flat approach angle is Woo’s version of quantifiable funk no doubt when the Mariners were looking over Brian Woo’s pitch tracking data they were enamored with his potential to create unorthodox angles his arm slot dropped throughout his college career and that drop continued as he turned pro and recovered from elbow surgery [Music] the lesson here is simple everything a pitch does is relative to the release point and arm angle the pitches with the most vertical break tend to be over-the-top deliveries with high release points like a Justin Verlander force or Tyler Glass now curve ball they need to get on top of the baseball to apply that backspin or top spin pitches with the most horizontal break often come from lower slot deliveries like a Christopher Sanchez two seam or Chris Sale slider creating a disconnect between the arm angle and pitch movement is a form of deception klay Holmes is over the top but throws a sinker with very little vertical movement aka ride but plenty of horizontal movement aka run tanner Scott’s fastball delivery meanwhile creates surprising ride from a 3/4 arm slot brian Woo’s arm slot is somewhere between 3/4 and sidearm in comparison to a true side armor like his teammate Luis Castillo yet despite a 12° difference in arm angle they still release from the same height this is because Woo glides down the mound and dips his shoulder and elbow more to get on top of the baseball giving his fastball more ride while Castillo’s has more run woo’s induced vertical break is relative to his delivery among all big league four seamers his is only 35th percentile in carry but 84th percentile among pitchers with a similar release height and 77th percentile among pitchers with a similar arm angle suddenly his below average pitch movement is above average with proper context taking into account that plus his VAAA and velocity you can see what Trent Blank and the Mariners saw hiding behind his unimpressive college erra woo also throws a seamshifted wake sinker to complement his four seamer he throws both pitches with the same velocity averaging 95 but the two seam trades off eight inches of induced vertical break for an additional eight inches of armside horizontal break perhaps what’s most impressive is how consistent he is with his arm angle and release point when throwing these two fast balls some four seam and two seam throwers have to vary their arm angle to get the desired effect seth Lugo thrower of many pitches is releasing his four seamer up here and his two seamer over there but Woo doesn’t cheat at all identical arm angle and release points for [Music] both the Mariners would have also observed Woo’s rapid improvement in strike throwing a trend that has continued since going pro his walk rate fell precipitously throughout his career at Calpali and in 2024 at the big league level he put together the sixth lowest walk rate of the last decade among pitchers with at least 100 innings he also had the highest percentage of pitches in the strike zone according to Statcast these numbers demonstrate control but what about command not all strikes are created equal so let’s make our own quick and dirty adjusted zone percentage middle middle doesn’t count that’s too dangerous but the edges of the strike zone should count as double this rewards pitchers for throwing strikes that are difficult to hit in our adjusted version of zone percentage the gap between first place Brian Woo and second place Joe Ryan is greater than the gap between Ryan and 24th place Dane Dunning in 2024 in particular he was just daring batters to hit his fast balls and they didn’t if he were throwing fast balls with bad qualities he’d be getting crushed but Woo has one of the highest swinging strike rates on his foresam among starters the last two seasons the sinker meanwhile is a soft contact generator one of the lowest average exit velocities in the same time frame woo secondaries are still a work in progress he added 3 in of armside fade on his change up between 2023 and 2024 which helped when facing lefties yet it might not have the velocity or movement to differentiate itself from the sinker left-handed hitters crushed him in his rookie year of 2023 but he dominated both sides of the platoon during his second big league season the sweeper in particular has blossomed against righties the fast balls are still very much his go-to pitches in most circumstances the Mariners have tended to target pitchers with great fastball qualities first and foremost that’s Logan Gilbert’s velocity and extension that’s Bryce Miller’s induced vertical break that’s Luis Castillo’s arm angle and release point and that’s George Kirby’s pinpoint strike throwing brian Woo is a special combination of all four no wonder Trent Blank wanted him first [Music] overall after his Tommy John surgery in April of 2021 Woo has ascended from injured struggling college reliever to sixthround pick to one of the more promising young starters in Major League Baseball during his career at Calpali he overlapped with six other big league pitchers in the Big West with more likely to come of those six Woo was by far the worst in terms of run prevention the college reliever to MLB starter path is also unorthodox in Woo’s short big league career 59 college draftes have served as starting rotation fixtures around the league and only six of them weren’t regularly starting during their draft year that pipeline tends to only work in reverse college and minor league starters who shift to the bullpen like most promising pitchers the only thing that can derail Brian Woo now is his arm health he’s already had Tommy John once and has a checkered injury history in the majors already he missed time in his 2023 debut season with forearm inflammation was shut down in spring training 2024 with elbow inflammation left his first start of 2024 early for precautionary reasons was scratched from a start in June and had an MRI while also missing time in the second half with hamstring issues but the simple fact of the matter is he’s already outperformed his draft slot by magnitudes he went 174th overall but has generated the 10th best war of the class to date and that’s with missing a pro year recovering from surgery if there was a 2021 class reddraft in 2025 maybe he wouldn’t go first overall like Trent Blank said but he’d go pretty darn high certainly well ahead of the actual first overall pick Pirates catcher Henry Davis as well as the second overall pick and first pitcher off the board Rangers righty Jack Lighter so whether he fully blossoms into a Sai Young candidate or not Brian Woo’s success is a win for the Mariners and a win for Data in [Music]