Entering 2019 Blake Treinen was locked into the A’s closers role, but after a dominant 2018 he completely fell flat and quickly lost his grip on the ninth inning. Ultimately finishing the year on the IL, he posted a 4.91 ERA and 1.62 WHIP over 58.2 IP and ceded the job to Liam Hendriks, who ran with it and seemingly emerged as one the elite:
85.0 IP, 1.80 ERA, 0.96 WHIP, 13.13 K/9, 2.22 BB/9
Can we really anticipate Hendriks replicating those numbers? Can we assume he’s going to remain the A’s closer? Or will he follow the same path as Treinen, only to regress and fall of the map after a dominant campaign.
In order to answer that, we need to look at the underlying skills:
It’s easy to explain why Hendriks saw a large spike in strikeouts, as he virtually shelved his sinker in favor of his fourseam fastball:
- 2018 – 48.21% fourseam, 21.75% sinker
- 2019 – 67.76% fourseam, 2.89% sinker
While the fourseam fastball isn’t necessarily a swing and miss pitch, the greater velocity likely further helps both his slider and curveball play up. It helped to lead to a 17.0% SwStr%, and while that may be extreme (he had an 11.32 K/9 in the first half) it helps to justify the elevated strikeout rate from his overall career mark (8.96 K/9).
Considering he owns a 2.42 career BB/9 and was at 3.14 or better after a slow start to the season, there’s every reason to believe that he can continue posting a strong BB/9.
Obviously shelving his sinker was going to lead to fewer groundballs, and it completely fell off a cliff to 31.3% last season. Surprisingly that didn’t lead to many home runs, with a 0.53 HR/9, but just how long can that really last? Pitching in Oakland may help, but that’s not enough to justify the elite mark.
The 85.7% strand rate looms extremely large. Sure relief pitchers have the potential to carry a better strand rate, but it also could regress in short order (and when the home runs start to plague him it will).
While the strikeouts are going to be there, it simply may not be at the level he posted last season. Couple that with the potential regression in his luck and home run rates and things could get ugly. While we wouldn’t go as far as saying that he’s going to post a similar implosion that we saw for Treinen, he’s a soon to be 31-year old who is coming off a career year. That really tells you all you need to know. Don’t be surprised if he loses his job before the All-Star Break.
Sources – Fangraphs, Brooks Baseball