The Mariners came into 2023 with what many thought would be a really solid rotation. With injuries to Robbie Ray and Marco Gonzales pretty early on in the year, the Mariners were forced to call upon their youngsters earlier than they probably hoped. I was pretty worried about the staff with such young and unproven guys in the back end of what was supposed to be the strength. But Bryan Woo stepped up and gave the Mariners some very valuable innings down the stretch, more than doubling his 2022 total.
Our first starting pitcher, Bryan Woo, checks in at #11 in our 2024 Mariners Player Rankings
Woo had a really solid 2022 season in the minor leagues, albeit in only 57 innings. But coming off Tommy John surgery, this was a good sign for Mariners fans. He had really good command and stuff with 13.3 K/9 and 3.5 BB/9, in route to showcasing the ability to become a solid starting pitcher. Coming into the 2023 season, many of us gave Woo a lot of value as a starting pitcher making his way through the high minors, and he was called up from AA Arkansas after only 44 innings.
Woo went on to throw 87 2/3 innings at the major league level over 18 starts. He had a 4.21 ERA, though Fangraphs had him at a 3.48 xERA. He was able to generate solid K numbers and control the zone pretty well with 9.5 K/9 and 3.2 BB/9. There were some up and downs as there are with any rookie starting pitcher, but given the lack of experience, just 57 professional innings pitched coming into 2023, Woo was really impressive.
If you head over to Woo's baseball savant page, it paints the picture of a pitcher who could really take some steps forward this year and jump into a new category. I mean, if you take his 87 2/3 innings and double it to approximately 170 innings, he is a 2-win pitcher as a rookie, that's pretty impressive. Where Woo really dominated in 2023 was with the fastball. According to Baseball Savant, he was in the 85th percentile in fastball run value, which contributed to a 30.3% whiff rate, and xBA of .192.
Woo threw 131 2/3 innings between the minor leagues and major leagues in 2023, so I don't think it's unrealistic to think that, if he can stay healthy, he could end up throwing 150-160 innings. If Woo can also continue to develop his off-speed pitches, mainly that cutter that was solid, we could be talking about a 2.5-win pitcher at your #5 spot in the rotation.