Justin Wilson is baseball’s most dominant ‘bad’ reliever

Tigers reliever Justin Wilson has had a rough August. In five appearances, the lefty has allowed three of the four home runs that make up his season total and given up eight runs in all. On the surface, Wilson’s 4.53 ERA makes his season look like just another chapter in the story of Detroit’s turbulent bullpen. However, it is kind of hard to identify why his results have been below average.

Wilson began the season in the closer conversation after the December trade that brought him to Detroit from the Yankees, and he lived up to the billing early in the year. Through May 1, not a run was scored while Wilson was on the field, as he struck out 15 and only walked two in 11.0 innings. In the 32.2 innings since, regression has occurred (and then some) — despite still striking out 25.2 percent of batters, he has an unsightly 6.06 ERA over that time.

In reality, 43.2 innings is still a fairly small sample, but typically you might expect to see some kind of a fluky indicator that shows where the runs have come from — an abnormal home run rate, for example. Here, Wilson has a pretty sound resume across the board. Among pitchers with at least 40 innings pitched, Wilson’s 23.9 K-BB rate is tied for 19th between Noah Syndergaard and Stephen Strasburg. Predictably, this means his 59 FIP- is also pretty good and is by far the best mark of any pitcher with a league average 100 ERA- or worse.

He’s got a great 55.8 percent groundball rate, which is about 23 percent better than the league average for relievers. His 59 FIP- and 60 xFIP- are almost exactly the same - he’s not the victim of an unusual home run rate. Batters haven’t even produced well against him — his .297 wOBA is also better than the league average. If you make a simple ranking of pitchers by their percentage of batters faced ending in positive outcomes (strikeouts + ground balls + pop-ups), he ranks 6th in baseball, just ahead of Clayton Kershaw, but his ERA- sticks out like a sore thumb.

Despite all that, there sits his 4.53 ERA, and his .355 BABIP. Regardless of where his true talent level lies, it’s kind of hard to figure out the sequence of events that lead to those runs, given the peripherals demonstrated above. Maybe this is truly one of baseball’s most pure examples of bad luck and sequencing.

However, there may be some other explanations to explore. Maybe the problem is his infielders not having the range to field a large number of singles, leading to a high BABIP? The sample is FAR too small to draw any conclusions about fielding statistics, but for what it is worth, we don’t see other Tigers pitchers uniformly experience this problem. Maybe Wilson is far worse from the stretch, and with runners on, the problems compound? In his career, there’s no noticeable split with runners on base, but during 2016, there is a bit of a change. With a sample so minuscule, there’s nothing to say about a change in his ability, but if trying to reconstruct the series of events leading to all those runs, poor luck with men on base is a reasonable explanation.

One explanation I’m considering (and is completely conjecture) is that of his pitch selection. This season, Justin Wilson has thrown a fastball or cutter 95 percent of the time. He throws hard and gets good movement on the pitches, but maybe he exposes himself a bit by not using an offspeed pitch. Maybe when 95 percent of pitches are at a fastball velocity (his four-seamer averages 96 mph while his cutter averages 91 mph), batters’ timing is never disrupted in the way it might be if they have to prepare for a 15 mph difference in velocity. Maybe batters are always jumping on mistakes because they’re already all-in on a pitch that speed. Maybe mistakes are more likely to happen in groups if his command isn’t working one night, and because of the above, he’s more apt to get damaged by it than other pitchers with his stuff.

I just used the word “maybe” a lot more in that paragraph than I’d like, so there’s a good chance that speculation is nothing. But I would be interested to see what would happen if he integrated a few more breaking balls into his pitch mix. Wilson already has a slider and a curveball — both have been used infrequently in 2016, but each has seen more regular use in past years. It’s never been a great pitch, but the curveball would most disrupt batters’ timing, and due to its vertical movement, it might see less of a platoon split than the slider.

Or maybe he doesn’t need to change. On paper, he’s already doing everything right.

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Spencer Bingol is a Contributing Editor at Beyond the Box Score. He can also be read at Crashburn Alley. You can follow him on Twitter at @SpencerBingol.