Treinen was one of the top closers off the board in many drafts, but was a massive disappointment. He ended up eventually losing the closer's job to Liam Hendriks. Treinen owned a 4.91 ERA, 1.62 WHIP and 59 strikeouts in 58 2/3 innings while providing 16 saves and six wins. He said he has had the issue for three weeks and thought he could pitch through it before an MRI revealed the stress reaction. Treinen is hoping to pitch again in the postseason.