Wednesday, October 28, 2015

2015 Season Review: Jordan Zimmermann

If it was possible for a starting pitcher on a high profile team like the Nationals to fly under the radar in 2015, it was Jordan Zimmermann. He didn’t throw a no hitter during the season to compete for headlines with Max Scherzer. He didn’t get demoted to the bullpen like Doug Fister. He didn’t fluctuate between the worst starting pitcher in the majors and the best starting pitcher in the majors like Stephen Strasburg. 2015 Jordan Zimmermann wasn’t even in the running for the Cy Young like 2014 Jordan Zimmermann. However, that doesn’t mean Zimmermann didn’t put up a good year. He did. It’s just that 2015 Zimmermann wasn’t quite as good as 2014 Zimmermann.


Compare Zimmermann’s performance in 2015 to his 2014 performance, and you find a solid yet unspectacular starting pitcher. His 3.66 ERA was top a 30 ERA among NL starting pitchers and his 3.0 WAR was top 25 among NL starters. That 2015 ERA, though, was a full run higher than Zimmermann’s 2.66 ERA, an ERA so good that he was mentioned in the 2014 Cy Young discussion.

Among the stats that didn’t change between 2014 and 2015 for Zimmermann are two that would indicate tough luck. First, BABIP (Batting Average on Balls In Play) could indicate bad luck or poor defense behind a pitcher. Zimmermann, though, posted identical BABIPs in 2014 and 2015 of .302, right in line with the league average. Second is Left On Base percentage (LOB%). This concept relates to the idea of cluster luck, that pitchers cannot control the order of the hits they allow and therefore cannot control the rate at which runners who reach base score. Zimmermann’s LOB% was actually a tick lower in 2015 at 75% than his 76% rate in 2014 and both are just slightly above league average. The consistencies between 2014 and 2015 end there, however.

The most noticeable change from 2014 to 2015 for Zimmermann was also the most discussed: fastball velocity. For most of Zimmermann’s post-Tommy John surgery career, he averaged 94+ MPH with his fastball and exactly 94 MPH during the 2014 season. In 2015, though, that velocity was down to 93 MPH, which was trouble for Zimmermann. Very few pitchers rely on their fastball as much as Zimmermann. Consider that major league starters on average use fastballs about 57% of the time. In that light, Zimmermann’s 2014 fastball usage rate of 70% is rather astounding. However, Zimmermann’s effectiveness with the fastball dropped off in 2015 along with his velocity.

For that reason, Zimmermann actually dropped the usage of his fastball down to 62.5% to counter the loss of velocity. In place of the extra fastballs, Zimmermann upped his usage of sliders to 22% and curveballs to 15%. Interestingly, though Zimmermann only threw changeups between 2-5% in previous season, he threw practically zero changeups during the 2015 season. For a changeup to be effective, it needs either a lot of movement or a noticeable velocity difference from the fastball. Since Zimmermann lost a tick on his fastball, it’s likely that his changeup would be closer in speed to his fastball and, therefore, less differentiated and less effective. Just based on pitch selection, it sure looks like Zimmermann recognized his diminished velocity and made adjustments to compensate for that.

However, that loss of velocity wasn’t a death knell for Zimmermann’s effectiveness. Always stingy with the free passes, Zimmermann posted a miniscule walk rate of 3.6% in 2014. In 2015, that went up to 4.7%, but that rate is line with Zimmermann’s previous few years and leaps and bounds below the league average. The same goes for Zimmerann’s strike out rate, which was 22.8% in 2014, his highest since his Tommy John surgery, that fell to 19.7% in 2015, again in line with his previous rates, 2014 excluded. That loss of strikeouts in 2015, though, resulted in the highest batting average allowed in Zimmermann’s career, and while the .260 batting allowed by Zimmermann during 2015 isn’t too shabby, it’s certainly a step back from the .242 batting average he allowed in 2014.

By far the biggest differentiator between 2015 and 2014 for Zimmermann, though, was in homeruns allowed. In 2014, only 6% of fly balls hit off of Zimmermann cleared the fence, a rather elite number. In 2015, though, Zimmermann’s performance regressed back to league average, as the HR/FB rate stat tends to do, of 11%. Of course, an extra bunch of homeruns will do some real damage to an otherwise solid ERA, but it's not as if Zimmermann suddenly came down with a case of homer-itis during the season either.

Now, all of that isn’t to say that Zimmermann didn’t perform worse in 2015 in areas that just might keep getting worse down the road. As a right handed pitcher who relies heavily on fastballs and sliders, Zimmermann is especially vulnerable to left handed hitters. That’s been the case for Zimmermann over his whole career and he has obviously mitigated that vulnerability enough to still be successful. However, 2015 saw a big drop off in his performance against lefties. After limiting lefties to a .290 wOBA in 2014 and a .308 wOBA in 2013, Zimmermann allowed a whopping .336 wOBA to left handed hitters in 2015. Adrian Beltre had a .337 wOBA in 2015, which means that left handed hitters who faced Zimmermann in 2015 turned into Adrian Beltre. Unless Zimmermann ups his usage of changeups (usually an effective pitch versus opposite handed hitters given its tailing action) or develops another plan of attack against left handed hitters, these struggles are likely to continue.

However, those struggles will probably come under the watch of a team other than the Nationals. While the team will certainly give Zimmermann a Qualifying Offer (QO), Zimmermann will also certainly turn down the QO. After failing to resign Zimmermann to a long term deal at any point over the last several seasons, the Nationals will see their star pitcher walk and pocket an extra draft pick in doing so.

Zimmermann will then enter the free agent market, but his future contract will not be weighed down by the draft pick compensation as much as someone like Denard Span as teams have shown a willingness to sacrifice that draft pick in order to get a front line starting pitcher. Zimmermann enters the 2016 free agent market as the third or fourth best starting pitcher available, just behind Zack Greinke and David Price and on par with Johnny Cueto. That means Zimmermann is probably gunning for a contract in line with those given to Lester and Scherzer that set the market for starting pitchers last off season. It will certainly be tough to see Zimmermann pitching in an uniform that doesn’t have a curly W, but the Nationals have a belief that they shouldn’t give out long term contracts to older pitchers with a Tommy John surgery and they are sticking to their guns, even when it comes to Zimmermann.

Previous 2015 Season Reviews:
Denard Span
Ian Desmond
Doug Fister

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