The Detroit Tigers added a number of new players this past offseason in attempts to replace departures and fix preexisting holes in each portion -- offense, starting pitching, relief pitching -- of their roster. Having already discussed the offense here, my focus here is on the new addition likely to have the largest effect on the pitching staff: former Washington Nationals starting pitcher Jordan Zimmermann.
As demonstrated last week in his spring training interview on MLB Network, Zimmermann has the personality of a post-Lions Silverdome hot dog, but the Tigers didn't sign him to a five-year contract so he would challenge Miguel Cabrera in the joke-telling department. All the team is asking Zimmermann to do is replace David Price's position in the starting rotation, which, sure, Jordan, you can borrow this book of limericks.
Zimmermann is unlikely to be mistaken for Price, but a recent comparison with another Vanderbilt alumnus, Sonny Gray, can serve as an entry point to the new Tiger's recent performance. <!--more-->Sonny is about four years Jordan's junior, but both entered 2015 with solid starter reputations, and both produced varied performances last season that introduced a degree of uncertainty with respect to their future expectations. From that article, here's Zimmermann's 2015 -- his worst season by WARP (2.2) since a torn ulnar collateral ligament and Tommy John surgery robbed him of significant portions of 2009, his rookie year, and 2010 -- divided into two roughly equal (in terms of innings pitched) portions:
Despite an increase in strikeout percentage while his walk rate held steady, the second "half" of 2015 did not go well for Zimmermann, whose ERA was worse by more than a run, something probably not unrelated to the fact that his home-run rate tripled. Even considering that pitchers generally seem to have little control over their home run/fly ball ratios, this is cause for concern. Unsurprisingly, Zimmermann posted his career-worst (again, not counting 2009-10) home-run-to-fly-ball (HR/FB) ratio in 2015 (data from FanGraphs):
If this spike indicates a trend that really is out of Zimmermann's control, there still may be some good news for him. According to ESPN, Detroit's Comerica Park was less homer-friendly than was Nationals Park in 2015, meaning that Zimmermann's new environment itself may mitigate this problem to some degree. Here's a visual comparison of the two parks:
Comerica Park is deeper to center and right-center, but tighter in the corners. How many of the 24 home runs Zimmermann allowed last year would have been home runs had he been pitching at his new home in Detroit?
On the first cut, we can only rule out two home runs, the ones that would've fallen short in left-center. It probably is fair to remove one more of these, that short one in the middle, at least on the basis that it -- an inside-the-parker by Aaron Altherr on a bloop misplayed by center fielder Michael Taylor -- wasn't the pitcher's fault. Still, most of the bombs Zimmermann allowed in 2015 were to the corners, and Comerica doesn't offer much relative dimensional help there.
Not all of the home runs Zimmermann allowed came in Nationals' home games, of course. In fact, exactly half came in road starts. As shown above, Comerica's dimensions are what they are, but, if we're feeling like optimistic Tigers fans, we may be able to shave off a few more of these home runs. For example, three of them were at mile-high Coors Field, one of which appears to have been substantially wind-aided. Because we're feeling generous, let's dump all three of those as well. Finally, Zimmermann allowed one homer at the famously friendly (and small) confines of Wrigley Field in 2015 on a windy day in late May that, if I'm reading the ESPN Home Run Tracker correctly, would not have been parked at any other stadium under more neutral weather conditions.
Using this most optimistic of razors to imagine how Jordan Zimmermann, Washington National, would have performed as Jordan Zimmermann, Detroit Tiger, vis-a-vis permitting home runs in 2015, we have trimmed his home run total from 24 to 17, thereby clipping his HR/FB ratio to a much more comfortable 7.49.
A premise of sorts for the foregoing comparative home run analysis was that the jump in Zimmermann's HR/FB ratio in 2015 was, in substantial part, the result of bad luck and outside of the pitcher's control. Zimmermann also posted his career-worst (2010 again excepted) xFIP, a measure that is designed to control for the usually random fluctuations in pitchers' HR/FB ratios, in 2015, though. In other words, it looks like something besides bad luck may have been to blame for Zimmermann's (relative) struggles last season.
Most articles written about Zimmermann this offseason touched on his pitch velocity and, more specifically, they noted a decline in velocity. Here's what the PitchF/X data at Brooks Baseball shows:
The above graph illustrates year-to-year maximum velocities for the three general types of pitches Zimmermann throws, and it's clear that his maximum fastball and changeup velocities dropped off in 2015 (his average breaking ball velocity also decreased from 2014 to 2015).
A pitcher's ability to mix speeds generally is as important as his ability to mix locations, but Zimmermann, who never had much use for a changeup, abandoned any lingering charade of reliance on offspeed stuff in 2015, turning to breaking pitches more than ever, even as their velocities converged with his hard pitches:
While the type of contact (line drives/ground balls/fly balls; pull/center/opposite field; and soft/medium/hard) Zimmermann allowed in 2015 wasn't a significant departure from career norms, the volume of overall contact increased, as indicated by across-the-board drops in whiff percentage:
Batters, it seems, had an easier time seeing and catching up to Zimmermann's (slower) pitches in 2015 than they had in the past.
Besides his recent velocity tumble, the other common concern with Zimmermann is that the right-hander always has performed noticeably worse against left-handed batters than he has against right-handed ones. Most pitchers are worse against opposite-handed hitting, but Zimmermann has been below average in that regard over most of his career, and his 2015 platoon split was worse than his career average:
If we're looking for signs of hope on this front, we may be able to find them by squinting our eyes and looking at this graph of Zimmermann's monthly platoon splits (by batting average):
While we should always expect variance in this regard, for Zimmermann, that variance seemed to stabilize in the middle of seasons, maybe suggesting that, once he's warmed up, and before he becomes too fatigued, he is capable of minimizing his platoon split. If that's true, it means there could be something there for new Tigers pitching coach Rich Dubee to work with.
Velocity decreases and HR/FB ratio increases can be indicia of coming or present-but-undiagnosed injury in pitchers, but they're even more common signs of ordinary pitcher aging, which, whatever you think about the 1,100 words you've just read, definitely is a thing that's happening to Zimmermann. If every pitcher eventually loses velocity as he ages, the question to ask is not whether a pitcher is going to lose velocity, but (whether and) how he will adjust to that unavoidable velocity loss.
Detroit's other big pitcher signing this offseason was 34-year-old reliever Francisco Rodriguez, who's entering his 15th major-league season. As FanGraphs' Jeff Sullivan pointed out when the Tigers signed K-Rod last year, Rodriguez has "survived for a long time, and he’s even thrived for a long time. You can only do that by adapting. Francisco Rodriguez is a tremendous example of how a pitcher should want to age." How has Rodriguez changed and adapted? Over the last 10 years, he's transformed from a flame thrower to a soft tosser, losing five miles per hour off his average fastball speed. Even so, his strikeout-to-walk ratio held steady. To maintain success as he aged, Rodriguez adapted by converting a fastball/breaking ball arsenal into one that favored a changeup:
By trying to fool hitters instead of simply blowing them away with the gas, Rodriguez has continued to succeed, even as his original tool set abandoned him.
Maybe this is why Zimmermann shifted his pitch mix last year, however slightly, away from his slowing fastballs and toward his curveball and slider. If this is an indication of conscious adaptation, it's an encouraging one that may provide a basis to believe that Zimmermann can outperform his projections this coming year.
It's worth remembering that, even though 2015 was, by his own standards, a bad year for Zimmermann, he has been and continued to be a solid starting pitcher (#32 or #43 among starting pitchers according to FanGraphs and Baseball Prospectus, respectively). Still, what do those projections think about Zimmermann in 2016?
Baseball Prospectus' PECOTA pegged Zimmermann as a low-2 WARP guy for a couple years now, and, for some of the reasons noted above, he came down to that level last season. ZiPS has found him a little more confounding and projects a relatively more substantial drop in terms of fWAR for 2016.
The good news for Zimmermann, his new teammates, and his new fans is that, even if the cynical projection systems are correct, Zimmermann will carry his weight as a solid, frontline starter. As optimistically suggested above, there also are reasons to believe he can outperform his lowered-but-still-good expectations in 2016, and helpful in that regard should be fellow starters Justin Verlander and Anibal Sanchez, both of whom are themselves working on ways to maintain success by adapting as they age.