At the end of April, Will Warren was contributing to the Yankees’ ongoing consistency issues, as they would lose games and have to tax their bullpen whenever he took the mound. The Yankees had lost five of his first seven starts, and while two of those losses should be blamed on the bullpen, there were clear flaws in his game that made him unreliable.
A 1.26 HR/9 and 11.5% walk rate meant that when Warren was on the mound, he would allow traffic while also being prone to giving up the longball, a dangerous combination that results in a high ERA. He looked like a young starter who had to figure out how to trust his stuff and go after hitters, and we’ve seen his confidence fully come around as of late.
A pitcher who is forcing hitters to expand the zone more than ever before, Will Warren has hit his stride, becoming a critcial part of this starting five.
Will Warren’s Brand New Curveball Is Taking Center Stage
The Yankees are an organization that has sat at the forefront of pitching development for years under the Sam Briend & Matt Blake regime.
From the Dominican Summer League up to the Major Leagues, the Yankees are staffed with excellent coaches who encourage innovation, and Will Warren is undergoing some interesting changes in the Bronx.
One of the new additions includes a brand-new curveball, a pitch that he has doubled the usage of over his last three starts, relying less on his four-seamer to carry the load.
This curveball has been remarkable for him, as hitters have a .154 average with zero extra base hits and a 56.5% Whiff%, and it’s his best pitch by Stuff+ (112).
His curveball has become a reliable breaking ball against lefties, allowing him to rely on the sweeper more as a right-handed weapon that he can occasionally throw to left-handed batters.
This puts less pressure on a changeup that hasn’t taken off yet, as Will Warren had to rely on his sweeper more against lefties than you’d like, given how poorly that pitch performs against them.
The shifts in pitch usage are based on an understanding of how right-handed hitters and left-handed hitters profile against these kinds of pitches.
By pitching to a hitter’s weakness, Warren constantly has an upper hand in a matchup because he can spin a ball in whichever direction the data suggests is effective against a specific hitter.
Warren has gotten better at this as the season has gone on, increasing his curveball usage against left-handed hitters and immediately seeing results.
Over his last three starts, Will Warren has thrown his curveball 20% of the time against lefties, as they’ve hit .182 against him with a 37.1% K% over that stretch.
It’s a real pitch for him, but it’s not the only thing fueling his breakout season in 2025.
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The Yankees Work Their Magic Again With the Sinker
Will Warren’s sinker hasn’t changed much from a movement or velocity standpoint, but he is using it differently compared to his 2024 season.
The right-hander has a much lower and wider release point than the average pitcher, creating a unique look with advantages and disadvantages.
His arm action makes his sinker less deceptive; pitchers who have a cross-body action tend to throw fastballs with sink and run, so Warren’s sinker is easier to read when it’s moving into righties or away from lefties.
The sinker on the right side looks like a strike as it approaches the plate and remains in the zone throughout its flight path.
On the right, Nolan Jones gets a sinker that starts out of hand as a strike and remains a strike throughout the pitch’s flight path.
There is no deception here; he knows it’s a pitch to hit from the second Warren release it, he launches it into the left centerfield gap for an RBI double.
Compare that to what we see on the left; Marcus Semien sees a sinker out of hand that does not look like it will be a strike, and it only becomes a strike at the last second.
Will Warren creates a delayed reaction that spares Marcus Semien no time to get his bat around and make contact, his best bet at that point is to hope the umpire blows the call.
There are two advantages that this shift from throwing sinkers that start as strikes to throwing sinkers that start as balls will create:
First, hitters are going to freeze and just take the pitch. Will Warren can immediately get count leverage or put a hitter away, and any time you can get a strike without the hitter swinging, it’s a win for the pitcher.
Secondly, it means hitters who do choose to swing will end up catching the pitch much earlier in their swing paths than they’d hope for, which we can measure with Baseball Savant’s new bat tracking data.
Last season, hitters had an 8° Attack Angle against the sinker with a 6° Launch Angle, but this year that has dropped to a 3° Attack Angle and a -1° Launch Angle.
Hitters aren’t trying to swing down more often against his sinker, but because they’re getting to this pitch later, they aren’t able to get the bat out in front to do much damage.
More groundballs lead to more double plays and easy outs, which gives Will Warren the confidence to pepper the zone against righties with this pitch.
It’s a subtle change, but it has had massive results for Warren, who has a sparkling 2.85 FIP and 3.22 SIERA on the season.
He has 17 more strikeouts than any other rookie pitcher with the second-best fWAR (1.1), and if he continues pitching the way he has as of late, Will Warren could truly become the next Michael King.