Toronto Blue Jays starting pitcher Trey Yesavage throws during the first inning of a baseball game against the Toronto Blue Jays, Sunday, Sept. 21, 2025, in Kansas City, Mo. (AP Photo/Charlie Riedel)
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There’s no mystery about what Toronto Blue Jays rookie starter Trey Yesavage is going to throw tonight in Game Six of the American League Championship Series. The only question is whether the Seattle Mariners can touch it.
Yesavage has turned heads this postseason with a split-finger fastball—known colloquially as a splitter—that’s unhittable when he’s commanding it well. Such was the case in his playoff debut against the New York Yankees, when he threw 5 1/3 no-hit innings with just one walk and 11 strikeouts. It wasn’t working as well in his next outing—ALCS Game Two against Seattle—when he allowed five runs in four innings.
Yesavage is the latest Blue Jays pitcher to rely heavily on his splitter. It’s still a lightly-used pitch across MLB, but it’s frequency has nearly doubled over the last four years from 1.6% in 2022 to 3.0% in 2025. Toronto pitchers throw far more of them than anyone else, leading MLB with a 9.4% splitter usage rate. No other team in MLB threw the pitch more than 7.7% of the time, and eight teams used it less than 1.0%.
A splitter is an offspeed pitch, designed to look like a fastball out of the pitcher’s hand, but with deceptively slower speed and sharp downward movement. It’s especially effective for pitchers with an over-the-top arm angle, and can be a a better weapon for certain pitchers than a changeup, which is the most common offspeed pitch in MLB. Splitters are much more popular in the Japan, South Korea, and Taiwan, so players who come to MLB from the Asian professional leagues often throw it, such as Kodai Senga of the New York Mets and Shota Imanaga of the Chicago Cubs.
Toronto’s splitter usage has jumped to 14.5% in the postseason, and it’ll climb even higher tonight after Yesavage pitches. He only made his MLB debut on September 15 and made just three regular-season starts, so he accounts for very little of their regular-season pitch usage stats, but he features his splitter 27.9% of the time.
Four Blue Jays pitchers who threw at least 60 innings had a splitter usage rate of 11.9% or higher during the regular season. That doesn’t include Yesavage, who only worked 14 1/3 innings, or reliever Seranthony Domínguez, who threw 21 innings after Toronto acquired him at the trade deadline and has a 15.0% splitter rate.
Kevin Gausman has been one of the game’s foremost splitter throwers for a long time. The 13-year veteran led all MLB starting pitchers with a 37.5% splitter rate, and it helped him compile a 3.59 ERA and 1.06 WHIP over 32 starts and 193 innings for the Blue Jays. He started Games One and Five of the ALCS, and he will be available out of the bullpen in Game Seven if Toronto wins tonight.
The splitter parade won’t necessarily stop when Yesavage leaves the game. Three of Toronto’s highest leverage relievers feature splitters prominently in their arsenals. That includes Domínguez, closer Jeff Hoffman, and setup man Yariel Rodríguez.
Toronto is one loss away from elimination, so Yesavage will need his best splitter tonight. If the Blue Jays win the next two games and advance to the World Series over the Mariners, the splitter will be a big reason why.