Why I’m still concerned about Bryan Woo

Q: What were Bryan Woo's recent pitching statistics?

In his last two games, Bryan Woo allowed 16 hits and six home runs while striking out only three batters.

Q: Why is Bryan Woo's sinker performance concerning?

Woo's sinker has dropped to a negative run value of -2.2 runs per 100 pitches, indicating a significant decline in effectiveness.

Q: How has Bryan Woo's pitch mix changed this season?

Woo has significantly reduced his sinker usage, throwing only seven in his last game, which is among the lowest in his career.

Q: What impact does Bryan Woo's sinker have on his overall pitching strategy?

The effectiveness of Woo's four-seamer relies on a complementary sinker to prevent hitters from sitting on it, making the decline in his sinker performance a major concern.

Apr 14, 2026; San Diego, California, USA; Seattle Mariners starting pitcher Bryan Woo (22) reacts after being called with a ball during the second inning against the San Diego Padres at Petco Park. Mandatory Credit: David Frerker-Imagn Images | David Frerker-Imagn Images Bryan Woo pitched the worst game of his career on April 25th and followed it up with another bottom-10 performance his next time out against the Royals. Combining the two outings, he struck out just three batters while surrendering 16 hits and six home runs. Six! So a lot of Mariners fans breathed a sigh of relief when Woo completed his turn against Atlanta on Wednesday with a line of 6 IP, 0 R, 1 H, 2 BB, 9 K. But personally, I’m still holding my breath. Here’s what’s bothering me:

Even for Bryan Woo, 66% is a lot of four-seamers. To be sure, he always throws a lot of fastballs, but he usually balances those four-seamers with a hefty dose of two-seamers. The seven sinkers Woo threw on Wednesday is the second-fewest he’s thrown in a game, *ever*. Has his sinker become a stinker? Run value would sure tell you so. After running solidly positive numbers on the pitch over his first three seasons, this year, his sinker has collapsed to being worth -2.2 runs per 100 pitches. And my concern has been magnified by the fact that the Mariners clearly see this issue too. Why else would they call for so few on Wednesday? I mentioned that game featured his second-fewest sinkers ever. Well, the third-fewest came in Woo’s prior game, when he threw seven in his first two innings, but just three over the entire rest of his outing. The team sees the bad results too, and they don’t think the problem is just going to go away. To be sure, the plan to simply dial the sinker way back did work on Wednesday. Once. But that band-aids don’t fix bullet holes. So what’s up with the sinker? Sinkers aren’t really meant to induce whiffs, but Woo’s is generating the lowest swing-and-miss rate of his career. Rather, pitchers tend to use sinkers to induce weak contact. And by that score, it’s been a bit of a fiasco. Combining his first three seasons, Woo allowed an xwOBAcon (expected damage on contact) of .322, whereas this year, that’s up to .419. It’s like he turned into Bobby Witt Jr. It’s hard to say why. The pitch shape really hasn’t changed that much. The velo’s the same, and he’s only getting the teensy-weensiest less run on it. The biggest difference is that he’s getting about an inch more drop, but that’s still a change of less than 5%. If you can spot the difference between the two pitches in this video, you’ve got a sharper eye than I do. While the shape has stayed pretty consistent, his command has faltered. His sinker works best when he throws it toward the bottom rail, but he’s been leaving a lot of them belt-high this season, which is consistent with guys getting the barrel to it more often. Maybe the issue is that he’s lost conviction in throwing the pitch. That’d help square the circle between the fact that he made a meaningful change in his pitch mix and that zeroed in on the mental game. “It felt like the last two starts, just trying to do too much, think too much, dive into scouting reports too much,” he said. “My best brand of baseball is . . . when it’s time to go on the mound, just go be. And I feel like I kind of got away from that the last two starts.” Whatever the reason, the deterioration of his sinker is a big deal because arsenals are complementary. His four-seamer is a great pitch, but it needs something to play off of to keep hitters from sitting on it. Even the truly exceptional pitchers who only really needed one pitch to thrive were relievers who didn’t have to face guys more than once. Woo’s arsenal has really needed that sinker to contrast with his four-seamer. Solutions are hard to come by. Despite how the Mariners brass talks about it, his breaking balls aren’t that good. He’s often gotten decent results with them, as he did against the Braves, but I think that’s an effect of using them sparingly. Hitters aren’t ready for those breaking balls. It’s not that the pitches themselves are all that good. One flag to plant here is that his changeup has looked better than ever, and maybe that can be the answer. But been that developing a better changeup is a good idea for Woo for years, and it’s just 34 changeups so far, so I don’t want to get over my skis on that. Another possible answer is that the issue really is what Woo hinted at: that it’s a question of throwing with conviction. That seems eminently fixable. And even if there is no answer, I can’t dismiss the possibility that this just doesn’t matter at all. He did just fine against the Braves—one of the best lineups in baseball—while throwing four-seamers two-thirds of the time. And I’ve long since not to doubt how Bryan Woo butters his bread. All this time it’s felt like it shouldn’t work, but it still did. Wombats poop in perfect cubes; some things are weird as hell and true anyway. That’s kind of Bryan Woo’s whole deal. But I can’t help but worry that the one start against the Braves was a magic trick. The Braves weren’t sitting on the four-seamer yet. Why would they when it was the first time Woo had committed to that pitch so strongly? If that becomes the norm, the scouting report will get out in a hurry and who knows what happens next. Tonight’s test against will tell us a lot. But until it’s over, I’m still holding my breath.