Keller flourished with the Cubs in 2025 after switching from a multi-inning relief role to a more traditional one with more one-inning appearances. This change came with a spike in velocity on Keller's four-seam fastball, which he threw a career-high 97.2 miles per hour on average (a difference of +3.4 mph from 2024). His strikeout rate also ballooned to a career-best 27.2 percent; a huge gain over his 17.9 percent mark for his career. The 30-year-old also blew his career 39.9 percent hard-hit rate out of the water, posting a 30.6 percent mark that was in the 99th percentile per Statcast. Keller's 0.33 ERA after the All-Star break was best among qualified relief pitchers, though his 2.39 SIERA ranked 16th during that span. The veteran is drawing interest on the free-agent market as both a starter and reliever, but he's a better bet to sign somewhere for a relief role, especially since he has a career 1.44 WHIP and 17.3 percent strikeout rate as a starter. Read Past Outlooks