Luke Weaver’s Sore Hamstring Trips Up Yankees Bullpen

Tireless reporter Jeff Passan of ESPN reported late Monday night that the hamstring pain that caused Yankees closer Luke Weaver to be held out of Sunday night’s game against the Dodgers would land him on the IL, for as long as 4-6 weeks, with a more specific timetable to be presented at a later time. The extent of Weaver’s injury was previously unknown, as he was still in the trainer’s room well after the final pitch, through the end of postgame media access.

Weaver has been nearly flawless all season — allowing just three runs in 25 2/3 innings across his 24 appearances, though two of those runs have come in his last three games — and in late April, he took over as the team’s closer for Devin Williams, who was removed from the role after his atrocious start. While Weaver’s microscopic 1.05 ERA probably isn’t for real, given his more “normal” 3.04 FIP, even the latter number makes him one of the most important members of the New York relief corps, and losing him for a significant amount of time is a blow. Weaver represents one of the most successful rotation-to-bullpen conversions in recent memory, going from a struggling journeyman starter, who was released and then later claimed on waivers in 2023, to being a candidate for his first All-Star appearance this July. Since his transitioning to the bullpen, which also came with a reinvention of his delivery that featured a minimalist windup, Weaver has put up a 2.46 ERA and a 3.26 FIP over 109 2/3 innings. He also gave up just one hit across his four World Series appearances last October.

While this can hardly be considered good news, the impact of the bad news is mitigated by a couple of factors. First, Weaver’s injury comes at a time when the Yankees have a 5 1/2-game lead in the AL East. That’s certainly not an insurmountable lead, but it’s a comfortable one at this point of the season. Back in April, our preseason projections had the Yankees with only a 31% chance of winning the division, and ZiPS was even less confident, at 24%. As of Tuesday morning, these divisional probabilities are at 89% and 86%, respectively. The ZiPS number factors in Weaver’s injury, projecting him to miss a full six weeks as the worst-case scenario, in order to illustrate this point: The Yankees only get a 0.8% percentage bump if he happens to miss the minimum amount of time before he can come off the IL, meaning they’re in fairly strong shape either way.

The second factor lessening the pain is that it’s far better to lose a pitcher to this type of injury now than a month from now. If instead Weaver had tweaked his hamstring in early July, the Yankees would have likely had to go into the trade deadline without fully knowing what his status would be down the stretch. If there should be complications due to the injury or he’s simply slower to heal than expected, they’d likely have an inkling that things were going poorly well before the All-Star break, which would thus provide them with plenty of time to decide how to address his extended absence.

Manager Aaron Boone confirmed on Tuesday morning that Williams will be the primary closer while Weaver is on the shelf. After some absolutely abysmal pitching during the season’s opening weeks, Williams has generally returned to form in his 15 appearances since.

There have been the usual rumbles in fandom about Williams’ wilting under New York pressure, but the more likely scenario is that he is an excellent relief pitcher who had a really lousy three weeks. I’ve looked at this issue in the past — maybe I’ll write an article at some point — since I have a vested interested in accurate projections, and found no historical tendency for acquired or signed Yankees underperforming or overperforming their projections as a group. This goes for both hitters and pitchers. Even Ed Whitson, the pitcher who keeps being brought up as the best demonstration of this effect, doesn’t really match up with the mythology! Of the projection systems housed here at FanGraphs, only THE BAT has given Williams a sizable ding to his projection since the start of the season.

Williams did nearly blow a save opportunity against the Angels last week, but at some point, you have to trust your best pitchers to take on important roles. And if not Williams, then who?

Mark Leiter Jr. has certainly made a case for being trusted in the highest-leverage roles, and he would absolutely be my top pick if Williams ends up struggling, but let’s not overthink things. This is Devin Williams — a two-time NL Reliever of the Year award winner, whom the Yankees acquired over the offseason to be their closer. He remains the man for the job.

Fernando Cruz has been absolutely fabulous since ditching his cutter and doling out more splitters than a divorce attorney. But he’s also spent the past 15 days on the IL due to shoulder pain, so bringing him back for an even more important role instantly comes with its own set of risks. If Williams should falter, then Cruz would still be available, with healthy innings under his belt.

Tim Hill remains a lefty specialist in the post-LOOGY age. He’s hardly a pitcher who baffles hitters, and his platoon splits are extreme and probably not going to improve because he lacks an out pitch against righty batters. To illustrate this point, lefty relievers who throw their offspeed pitches (changeups or splitters) less than 3% of the time in 2025, such as Hill, have performed on average 77 points of OPS better against lefty batters than they have when facing righties. Lefty relievers who throw an offspeed pitch at least 3% of the time have averaged a 35-point platoon split.

Jonathan Loáisiga may be a candidate at some point, but he’s had mixed results since his return from Tommy John surgery in mid-May. I liked Ian Hamilton enough coming into the season to have him on my breakouts list, but his 14.8% walk rate certainly won’t cut it.

It wouldn’t be a bad idea for the Yankees to add another high-leverage arm or two to the back of their bullpen for the stretch run, but that would be less out of necessity and more because it’s always smart for a contending club to bolster its bullpen before the trade deadline. Regardless, short of any nasty surprises, it’s unlikely that Weaver’s injury will derail their season or represent a significant change in his outlook upon his return.