You can bet that I am now fully invested in his future at the big league level.
Hildenberger was astounding in 2017, rarely do you ever see a reliever with an elite groundball rate (58.8%) and great peripherals also (2.92 xFIP). Hildenberger was in the top 15 for relievers with at least 40 innings pitched in 2017 for both of those stats respectively and it seemed like the Twins had a future elite reliever.
2018 started in a similar way for Hildenberger as he held a 2.06 ERA in late June and had only allowed more than one run in a single outing just once. That is, until the game from hell on June 30th. Recall, if you will, the series against the Cubs in 2018 where Willians Astudillo made his major league debut, every game ended up in a shootout, and players dropped so much due to the heat that the ending outfield was Logan Morrison-Willians Astudillo-Robbie Grossman. Beyond that butcher of a defense was a nightmare outing for Hildenberger in which he walked four batters, gave up four hits, allowed five earned runs, and only got one out. His ERA on the season shot up from that 2.06 mark to 3.18 and he hasn’t been the same pitcher since.
It would be dramatic for me to imply that a single outing was the turning point in a career but perhaps the outing was more of a symbolic pivot in which the Cubs became the first team to make it apparent that Hildenberger was beatable. The numbers are incredibly eye-opening as in 81 ⅓ major league innings before the outing his ERA/FIP/xFIP slashline was 2.66/3.44/3.26 and his groundball rate was 54.5%. Starting with that outing through his most recent appearance on September 21st in 2019 his slashline becomes 9.72/5.12/4.41 with a groundball rate of just 40.9% over 50 innings.
I think I speak for most Twins fans when I ask; “what the hell happened”?
The first thing to look at is his pitch mix which is a fairly standard sinker, slider, and changeup combo with the occasional over-the-top four-seam fastball to keep hitters on their toes. His slider has never been that good by pVAL (pitch value) but his sinker/changeup combo was what allowed him to be dominant to start his career which leads me to believe that somehow that combo has gotten worse. His changeup pVAL was still elite in 2018 but his fastball quality went into the toilet despite gaining a small tick of velocity. Why could this be? Well, let’s take a gander at some heatmaps and oh:
There’s a significant shift more towards the outside of the plate vs righties and inside vs lefties. The general stereotype is that lefties love it down and in and perhaps throwing more outside to righties allows them to get extended and hit the ball harder than when he was going in earlier in his career. Granted, this may not be “the” thing but it certainly is “a” thing, pitching is more complicated than just a single pitch losing its location.
No matter what, Hildenberger does not have much room for error if he wants to continue his major league career. He’ll likely start the year at AAA and be one of the first arms called upon when the inevitable bullpen shuffle occurs but any success is far from guaranteed and all anyone can hope for is that the Trevor Hildenberger of old is still somewhere in there.
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