Sinister sweeper should have the NY Mets all over this reliever this offseason

The New York Mets will likely be on the lookout for relief pitching help this offseason, and one of the more under-the-radar names that will be hitting the open market is right-hander Brad Keller. Keller had spent the first seven years of his MLB career as a starter/reliever type with varying results. However, in 2025 with the Chicago Cubs, Keller had a massive season, and if you were a right-handed batter, his sweeper was a spooky pitch to face.

Keller put up a 2.07 ERA, 2.94 FIP, and 0.96 WHIP over 69.2 innings of work. His 27.2% strikeout rate was by far the best of his career. So was his 26.9% whiff rate. On top of that, he put up a respectable 8% walk rate and got batters to chase 30.4% of the time, which was yet another career best. When batters did make contact vs Keller, it was typically weak contact. He was in the 99th percentile of exit velocity, at 86.7 MPH, and the 86th percentile of barrel rate at 5.8%. That led to an HR/9 of 0.52.

All of Keller’s pitches were effective offerings, but nothing was more deadly than his sweeper this season. Opponents only hit .073 with a .086 slugging percentage and a wOBA of .093. So far, he is the only pitcher whose sweeper registered a sub-.100 BA, SLG%, and wOBA in the Statcast Era (min. 40 plate appearances and not including the shortened 2020 campaign). Keller got batters to whiff at his sweeper 46.3% of the time, which was the 9th highest in baseball in 2025 (min. 100 sweepers thrown).

Brad Keller's sweeper was one of baseball's most effective breaking offerings in 2025.

It’s not as if this was dumb luck either. In the rare instances batters did make contact vs Keller’s sweeper, he induced an exit velocity of just 82.5 MPH. His xwOBA on his sweeper was still outstanding at .102. No pitcher who threw a sweeper 100+ times in 2025 had a lower mark, with the second closest being Trevor Rogers at .128. 

Keller can thank the added velocity to his sweeper, going from 84 MPH in 2023 and 2024, to around 86 MPH in 2025 with the Cubs. Although the pitch lost vertical movement, dropping to 33.7 inches, it maintained similar horizontal break from 2024, averaging out at 14.1 inches. The only criticism one could make about Keller’s sweeper is that he only used it against right-handed batters. Of the 148 sweepers he threw in 2025, only eight were against lefties.

But the pitch he used against lefties was also highly effective. His low-90s change-up held opponents to a .189 BA, a .216 slugging percentage, and .216 wOBA. It was another pitch in his arsenal that induced a ton of swings and misses, with a 39.7% whiff rate. Batters had a negative launch angle at -4. Plus batters had an 82.4 MPH exit velocity against it. His .227 xwOBA indicated luck barely played a factor in the effectiveness of Keller’s change-up. Like his sweeper, Keller sacrificed vertical drop on his change-up to gain more velocity and horizontal movement. Between the 278 sweepers and change-ups Keller threw, he allowed only 10 hits, with only one extra-base hit —a double. He also induced 35 K’s between the two offerings. 

Facing Keller’s sweeper must have been a scary experience for opposing hitters, given how little they hit the ball and how often it was poor contact. The fact that he had an offspeed pitch nearly as effective as his sweeper just for left-handed batters also made him an intimidating presence on the mound. The Mets need another reliever in their bullpen. Even if they re-sign Edwin Diaz, their best set-up options include Brooks Raley and A.J. Minter. Plus, Keller was named as a potential free agent the Mets would land this offseason by Jim Bowden. Given how effective Keller was in 2025 with the Cubs, he should be the Mets’ go-to answer for the 8th inning next year.