His 91.6 mph fastball plays up big off his changeup — hitters can't locate either pitch cleanly. Four earned runs over his last 18 innings with a 12-K outing against Kansas City headlining the stretch. The top streaming arm on the wire this week.

His sweeper runs a 39.5% whiff rate — among the best for any single pitch in baseball right now. Beat the Yankees on July 7 in six innings. The Rays have an elite track record with arms just like this; add in all formats before ownership catches up.

Seymour spent his first two months in a non-descript relief role but has emerged as one of Tampa's most consistent starters over the past five outings. His K rate has jumped from 24.7% to 29.1% in that stretch, and exit velocity suppression at 87.9 mph confirms the contact quality is real. The full-season 4.02 ERA oversells the risk — strip out two rough early appearances and this profiles as a low-3s ERA arm with improving stuff. Clear add in 12-teamers; borderline in 10-team leagues depending on SP depth.

Seymour opened 2026 in Tampa's bullpen but has been stretched out as a bulk-starter since early June and has been electric in that role: 2.84 ERA, 0.79 WHIP, 19/5 K/BB in 19 innings. His changeup is a genuine weapon (.141 BA against, .197 SLG) and he's been averaging close to a strikeout per inning. At 25% ownership while functioning as a rotation piece, he's one of the clearest market inefficiencies in deeper leagues. Add in 14+ team leagues while the Rays keep sending him out as a starter.

Started vs Boston Red Sox (3W-0L, 5.23 ERA)