Brad Keller is a New Man, and the Cubs Have a New Relief Weapon

Brad Keller was ineffective over the last two seasons, bouncing between the Royals, Red Sox, and White Sox. Becoming a new pitcher at age 29 is always unlikely, but in his brief debut with the Cubs, anything appears possible.

Keller is known as a ground-ball specialist whose fastball had settled into the low 90s. He transitioned to the bullpen in 2024, and didn’t see much success. His fastball didn’t see the boost that sometimes comes with a transition into shorter stints, and he looked like largely the same pitcher who struggled in the Royals rotation in 2023.

So far in 2025, it’s worth asking whether that expected boost in stuff lagged a year behind. Brad Keller has looked like a new man, and it appears that the Cubs have found a quality reliever in the bargain bin.

Keller has never had the kind of velocity he’s shown so far this season, and it’s hard not to wonder whether we should be looking at him as an entirely different pitcher. In addition to his velocity increase, his fastball has added over 100 rpm of spin. That's to be expected—those numbers are almost always tightly correlated on the fastball—but it underscores the fact that this appears to have staying power.

The Stuff+ on his heater has only improved from 88 last season to a still-unimpressive 90, but it may be the rest of his repertoire that reaps the benefit of his newfound zip. Keller’s Stuff+ as a whole has jumped to 111. With a measure of 100 being average, he’s never posted a Stuff+ better than 98. His slider has improved the most, grading out as an elite 136. Adding velocity doesn’t always improve the fastball itself, but hitters having to react that much quicker can have a widespread effect on the rest of a pitch mix.

Keller barely used his sinker in 2024, throwing it only 5.1% of the time, and for good reason. The pitch allowed a 1.286 slugging percentage last season. The sinker usage has jumped to 19% in 2025, despite looking like the same pitch in terms of movement and velocity. The big difference is the 3+ mph of separation between the two fastballs, which could be enough to keep hitters uncomfortable and bring back the ground balls. When a four-seamer is that much faster than a sinker, the latter becomes almost like a splinker, a la Jhoan Durán or Paul Skenes.

If Keller can maintain this velocity, he could be another big bullpen find for the Cubs. While it’s a tiny sample size, nothing sounds like the potential breakout alarm quite like a significant spike in fastball velocity. With his current pitch mix (one that includes the tools to induce ground balls and retire hitters on both sides of the plate), Keller may have finally found the piece of the puzzle he's been missing the last few years.

Brad Keller is worth watching very closely in the early going this season. Seeing his heater approach 99 mph is undoubtedly fun, but the rest of his repertoire could soar to new heights as a result. Is it worth being more than cautiously optimistic this early in the season? Is it even worth discussing, before we see a bit more from him? Let us know below!