Though the Detroit Tigers entered 2016 with a trio of young, promising starters, the hope for the rotation rested in the right arms of Justin Verlander and Jordan Zimmermann. The latter was a huge offseason acquisition, signing a five-year, $110 million deal in November, signaling that the team was indeed set on being a serious contender once again.
Zimmermann came to Detroit after seven strong seasons with the Washington Nationals, serving as a full-time starter for the most recent five. His numbers speak for themselves: he ranked in the top 30 in ERA, FIP, and WHIP from 2011 to 2015 and sat 12th among qualified starters with 18.7 fWAR. Zimmermann transitioned seamlessly to Detroit. He was named American League Pitcher of the Month for April 2016 and gave up just two earned runs in his first five starts with the Tigers, spanning 31 innings.
Unfortunately, it did not take long for things to turn sour. Zimmermann suffered a groin issue in late May and returned to the rotation after one missed start, but endured a horrible June with a 6.34 ERA. He later went on the disabled list with a neck strain which bothered him for the rest of the season. He made just four starts from August onward with little effectiveness. Zimmermann ended his first year with the Tigers after a modest 18 starts, posting a 4.87 ERA and 4.42 FIP.
The results speak pretty clearly: Zimmermann was not himself after his injuries. After an electric start to the season which seemed right in line with his time in Washington, the righty’s ability to pitch effectively was completely zapped. The biggest evidence for this is seen in his strikeout and walk rates, both which jumped in the wrong direction. While not a huge strikeout pitcher, Zimmermann sat at just 12.8 percent after his injuries, down from 19.8 percent with the Nationals and 16.3 percent to start the season. Meanwhile, his walk rate was up almost three percentage points from where it normally lies.
This lack of command is the most concerning aspect of Zimmermann’s performance last season. While opponents hit an unusually high .321 against him after his injuries, they made hard contact at a similar rate and had similar line drive, ground ball, and fly ball ratios. Similarly, opposing batters were swinging and connecting at very similar rates before and after his injury. While batted balls were a problem, they do not tell the whole story.
Health and adaptation
It would be tempting to say that all Zimmermann needs to do is be healthy to be effective in 2017. That in itself is no small feat, although apparently he is on the right track so far. “So far, I feel strong, I feel healthy and I’m ready to go,” recounted Jeff Seidel of the Detroit Free Press soon after the Tigers reported to Florida. While taking a player’s self-assessment as medical truth is a dangerous game, at least the signs are positive going into spring training.
But even if Zimmermann is completely healthy, there still is some cause for concern. From 2011 to 2015, Zimmermann averaged at least 93 mph on his fastball; in 2016, he averaged below this, both before and after his injury. Granted, perhaps some of his earlier starts represented a warming up into the season, but either way, his velocity was lower than in previous years. Likewise, 2016 saw the least amount of action on his slider and curveball, with both pitches showing much less horizontal movement and less consistent vertical action as compared to past seasons.
One season — really, two partial seasons — is not enough to make significantly judgments from, but the numbers are worth keeping an eye on. Even during his excellent start to last year, Zimmermann was striking out over a batter less per nine innings than he did in previous seasons. If his velocity and movement both struggle to return to that of his earlier days, there might be a problem going forward.
Zimmermann’s health will be one of the more closely watched factors in Tigers camp this spring and will be tracked well into the season. If his neck begins to bother him again, do not expect very strong numbers from the starter. But even if Zimmermann is back to full strength, his pitch data is still something to keep an eye on. Even before his injuries last year, he started showing a slight decline. However, he seemed to do just fine with what he threw, so maybe he can survive with a different strategy going forward.