Keller underwent right elbow UCL reconstruction surgery with internal brace and flexor tendon repair Tuesday, Lochlahn March of The Philadelphia Inquirer reports.
Keller was diagnosed with a torn UCL in his right elbow just after the All-Star break and has now officially gone under the knife. He's expected to be sidelined 13-to-16 months from Tuesday's surgery, so the earliest that he could return to action will be late in the 2027 season, though it's more likely that he'll be aiming toward being fully healthy for the start of the 2028 campaign. Keller will finish the 2026 regular season with a 4.02 ERA, 1.34 WHIP, 13 holds, three saves and a 32:13 K:BB across 31.1 innings.