Tigers need Justin Wilson to stay strong throughout the season

An up-and-down first season with the Detroit Tigers was not enough to slow expectations for Justin Wilson coming into 2017. In a bullpen lacking consistent relievers, Wilson is one of the few bright spots. His debut season with the Tigers looked to be similar to his previous endeavors with both the Pirates and Yankees, but he sharply faded down the stretch.

Tigers manager Brad Ausmus likes to stick to a script to close out games, so after Bruce Rondon was sent down to the minors very early in the year, Wilson will have plenty of opportunities to pitch in crucial situations. So far, five of his seven appearances this year have come in the eighth or later, and he has settled into the setup role ahead of Francisco Rodriguez. Unless things fall apart again, he will call this home for the foreseeable future.

2016 was a tale of two halves for Wilson. After a very strong first three months to the season, everything fell apart from July onward. His ERA and FIP both ballooned, no thanks to a decreased strikeout rate and a sizable jump in walk rate and batting average allowed. While his 0.28 WPA and 1.24 RE24 in the first half were not otherworldly, these numbers plummeted to -0.93 WAP and -6.72 RE24 in the second half.

Though the overall results varied greatly, Wilson’s velocity was mostly steady between the two halves, and opponents generated less hard contact and more soft contact against him. Still, there was a sharp change in the type of contact opponents were making. From July onward, batters hit line drives under nine percent of the time, down from 22 percent earlier in the year. In their place was a huge jump in fly balls, and with them a big jump in home runs.

Wilson’s second half of 2016 falls closer to his career numbers than those from earlier on in the season. While his ERA and FIP both sit a little above 3.00 from 2012 to 2015, he posted an 8.71 K/9 and 3.66 BB/9 over that span, figures that are remarkably close to those from July to October 2016. His career win probability numbers are much more favorable than those from last season, though.

While the overall numbers indicate that Wilson’s great start may have been a hot streak, a deeper look at his career shows a different trend. Since coming to the majors, the lefty has been consistently better in the first half of the season than the second. His ERA, FIP, WHIP, batting average against, wOBA against, K/99, and BB/9 are all worst off during the latter part of the season.

Many of the numbers from last season fall into this pattern. Wilson has typically traded ground balls and line drives for fly balls as the season progresses, and his home run to fly ball ratio jumps as it did in 2016. While opponents are not generating any harder contact against him, they are still finding much more success in their results.

Wilson suffered from some elbow issues in 2016, which did not significantly affect his availability but did likely affect his performance. When looking at his first and second half splits over the course of his career, there is a decent argument regarding fatigue as the season goes on. For a player with four seasons under his belt, this trend is not encouraging. Wilson believes he made changes to his conditioning regimen that will improve his endurance, but he’ll have to prove it over a full season.

2017 will be an important season for Wilson, especially given his prominent position in the bullpen. He has started off strongly, with a perfect ERA and good strikeout and win probability numbers, but his walk rate is elevated. He also is above his average line drive and fly ball rates, but he has yet to give up a homer. In fact, through 6 ¹⁄₃ innings, he’s yet to even allow a hit of any kind.

However, Wilson has a career 1.29 ERA in April. Another positive start is a good sign, but this is nothing new. For the Tigers bullpen to be successful — or even competent — Wilson must find a way to carry this throughout the season. How he performs from July onward will be a key to watch for this summer.