Justin Wilson’s fastball regressed in 2016

Justin Wilson’s four-seam fastball was not good in 2016. Despite being one of the best pitches in baseball in 2015, it was terrible this past season. In 2016, his four-seam had a Fangraphs pitch value of -1.6, compared to 10.8 in 2015 (zero is average). On the surface, this doesn’t make much sense. Wilson didn’t lose any velocity on his fastball over the past year, so how was it so much worse? Let’s take a look.

The first thing to look at is spin rate and movement to figure out if there was anything fundamentally wrong with Wilson’s four-seamer. Surprisingly, his spin rate improved from last year. He gained almost 100 rpm on the fastball since 2015. The movement on the pitch was nearly identical as well. Therefore, neither was the issue.

When we look at the locations of the pitches Wilson threw in 2016 compared to previous years, we find one source of the issue. His biggest problem in 2016 seems to be a lack of fastball command. This means he generally kept the ball in the strike zone, but had difficulty throwing the ball where he wanted it within the zone.

While these charts show all of the pitches he threw rather than just four-seam fastballs, they do bring attention to some significant problems. Most of the pitches Wilson throws are either four-seamers or cutters, and Wilson is a pitcher that relies on a high backspin rate. These kinds of pitchers keep their fastballs near the top of the strike zone to get the deception they need to be effective. We see from the charts that in 2014 and 2015, Wilson was able to keep his pitches in all areas of the strike zone, but in 2016 he threw a lot of pitches at and under the bottom of the zone.

In line with this, Wilson’s batting average on balls in play (BABIP) jumped from .301 in 2015 to .340 in 2016. Hitters saw the fastball much better, as it was at the bottom of the zone where they expected it instead of at the top of the zone. In addition, the Tigers’ defense was not very good and did virtually nothing to bail out Wilson (and the rest of the pitching staff, for that matter).

Wilson struck out 10 batters per nine innings in 2016 (MLB average was 8.1 strikeouts per nine), but struggled in 1-2 counts. Over 12 percent of Wilson’s 1-2 pitches resulted in hits, and just under six percent were put in play some other way. As a team, the Tigers gave up hits on less than seven percent of all the 1-2 pitches thrown in 2016. In addition, Detroit induced nearly three times as many balls in play that did not fall for hits (basically outs) than Wilson alone; almost 15 percent of the Tigers’ 1-2 pitches were in play but not hits.

Nearly 58 percent of the pitches Wilson threw in 1-2 counts were four-seam fastballs; 34 percent were cutters. His batting average against (BAA) on the cutter in this count was only .154, so that wasn’t the issue. When we look at the stats on the four-seam fastball we find our answer. His BAA on the four-seam in a 1-2 count was .412. That is significant because of the sheer number of four-seams he threw in that count.

Digging a bit deeper, we discover that Wilson’s overall numbers with the four-seam weren’t very good.

Wilson’s four-seam got lit up in almost every count, especially on the first pitch. This is interesting, as the four-seam has always been one of his best pitches, if not his best. As previously mentioned, the pitch had a Fangraphs pitch value of -1.6 in 2016 compared to 10.8 in 2015.

One item of note is that Wilson was much better against right-handed hitters than he was against left-handed hitters. Against righties, he had an ERA of 3.38 and a .232 BAA. Wilson’s ERA was 5.48 with a BAA of .308 against lefties. This is unusual, as most left-handed batters have a difficult time hitting left-handed pitching. When we go back to the charts, however, we realize this is because the fastballs were low and inside to righties and low and outside to lefties. Inside pitches are much more difficult to hit, so it makes sense that right-handed batters would have more trouble hitting Wilson’s fastballs than left-handed batters.

Considering Wilson’s fastball command issues, he didn’t perform too poorly last season. He gave up less than one home run per nine innings (MLB average in 2016 was 1.2 home runs per nine) and walked only 2.6 batters per nine (compared to the league average of 3.1) despite his lack of command. Hopefully he can correct his fastball command in 2017 and return to the pitcher he once was.