Detroit Tigers Need To Be Wary of Potential Regression From Reliever’s Hot Start

Bullpens can be volatile, even ones as good as what the Detroit Tigers have put together.

Detroit Tigers pitcher Tommy Kahnle (43) throws against Kansas City Royals during the eighth inning at Comerica Park in Detroit on Thursday, April 17, 2025. | Junfu Han / USA TODAY NETWORK via Imagn Images

The Detroit Tigers have been excellent to start the 2025 MLB regular season.

They are receiving contributions from players up and down the roster. Areas that were considered weaknesses heading into the offseason are no longer categorized as such with the team owning a 22-13 record entering play on May 7.

The offense is producing more than enough runs for a pitching staff that has carried its elite production over from 2024 into 2025.

A team ERA of 2.96 is the best in baseball, mowing down opponents with regularity. Their starting rotation has been great and the bullpen has picked up right where it left off last year, despite some new faces being in the mix.

One of the additions that were made in free agency that has paid major dividends already is Tommy Kahnle.

He signed a one-year deal with the team after spending the last two seasons with the New York Yankees, leaving the pinstripes and joining the Tigers just like his former teammate, Gleyber Torres.

Both players have performed at a high level with Detroit.

On the mound, Kahnle has assumed a key role at the back end of the bullpen and has thrived. He leads the Tigers with five saves and has also recorded two holds.

Opponents have been shut down by him all year long, allowing only four hits and three walks, resulting in two runs scored, only one of which was earned, in 12.2 innings, resulting in an impressive 0.71 ERA. 

He has struck out 12, producing a 0.5 WAR, and has an eye-popping 567 ERA+, which is the best on the team.

While the start has been incredibly impressive, Detroit needs to be wary of regression coming at some point.

Can Tommy Kahnle Keep Dominating Despite Underlying Metrics?

As shared by Eno Sarris of The Athletic (subscription required), Kahnle has some of the worst Stuff+ numbers for a relief pitcher with at least three saves.

His Stuff+ of 93 is tied for the second worst with Ryan Pressly of the Chicago Cubs; only Luke Jackson of the Texas Rangers is lower with an 87.

To this point, Kahnle has been finding success with truly elite offspeed pitches. His +6 Offspeed Run Value is the best in baseball in the 100th percentile.

That is clearly a suitable weapon for him to succeed with, but a lot of success for relievers over the long run is tied to velocity. He relies almost exclusively on a changeup right now, throwing it 84% of the time.

Kahnle has thrown so few fastballs that he hasn’t qualified for Fastball Velo stats on Baseball Savant. Had he thrown enough, his score would be well below average.

Currently, he is in the top 1% of multiple statistics, which speaks volumes to just how good his changeup has been. Relievers can succeed relying on one pitch, but if opponents start figuring that out, where will Kahnle turn to?

The Tigers obviously hope his dominance continues, but they need to be prepared and have contingency plans in place if his raw numbers start to reflect what his Sutff+ insinuates more closely.