Isaac MattsonPIT · RP

2026 review

Isaac Mattson was a middle-relief arm who didn't miss bats and didn't miss the middle of the plate either, working to a 5.35 ERA and 1.60 WHIP in 38.2 IP for PIT with a 20.5 K% and 10.2 BB% over 176 BF across 38 games. He was optioned and recalled repeatedly through the year, on May 20, Jun 13, Jul 29, Aug 1, Aug 2, Aug 13 and Aug 18, then recalled again Sep 4 before a right hip impingement put him on the 15-day IL Sep 8 with no activation on record through Sep 27, 19 regular-season days missed. Taken in just 42 of 674 drafts at ADP rank 930, he finished 1093rd of 1472 overall and 714th of 811 pitchers, 539th of 575 relievers. His fastball ticked up from 93.9 mph Mar-Jun to 94.7 mph Jul-Sep, and his 5.35 ERA ran 0.88 below his 6.23 xERA over 176 BF. The TDK LABS card flagged an ugly outing in early May, then by mid-Aug had him as a recent recall with strong minor-league metrics but a low-leverage middle-relief role, and by late Sep was still tracking the hip issue.