Jordan Zimmermann, Now With Strikeouts
Despite possessing above average fastball velocity, Jordan Zimmermann has generally posted strikeout rates right around the league average. Part of the reason for the disappointing strikeout totals is because he throws his fastball quite frequently. From 2011 to 2013, his fastball usage ranked 29th among 125 qualified starters. We know that the fastball easily sports the lowest SwStk% among all pitch types. So throwing the pitch often is naturally going to result in fewer swings and misses on average.
Prior to 2013, Zimmermann’s secondary pitches weren’t very good at generating swings and misses. Both his slider and curve induced swinging strikes at a below average clip. The former failed to make up for the lack of whiffs by inducing grounders, while the curve ultimately proved to be a decent pitch because it offset its lack of whiffs with its ability to generate lots of grounders.
Then in 2013, the results on his slider improved dramatically, as it was suddenly generating an above average rate of swinging strikes. That improvement continued into 2014, as the pitch’s SwStk% jumped again. But the real driver of Zimmermann’s strikeout rate surge was his fastball. The pitch’s SwStk% remained in a tight range between 6.2% and 6.4% from 2011 to 2013, but rose to 8.4% in 2014. He also upped his usage of the pitch to over 70%, ranking fourth among all qualified starters.
You usually don’t see increased fastball usage coinciding with a spike in strikeout rate. The velocity on the pitch remained identical to his mark since 2012, so it’s curious how he was suddenly able to induce so many more swings and misses with the pitch. The smart money says to expect some regression here without any obvious explanation for why the pitch was so much more effective.
The risk is that if the fastball returns to its previous SwStk% level, but he decides to continue throwing it 70% of the time, his strikeout rate may actually drop below his 2011-2013 levels. Though, a better slider could curb some of that downside.
Of course, even if his strikeout rate does drop back, his control is so good that he’s going to remain a good pitcher. His overall strike percentage ranked third in baseball this season and fifth last year. And since 2012, he ranks third in F-Strike%. That type of strike-throwing ability should help him maintain a sub-5% walk rate.
Aside from questions surrounding the sustainability of his increased strikeout rate, one wonders how much longer he can continue to outperform his SIERA marks. Except for this year, he has always posted below average BABIP marks, despite allowing high line drive rates since 2012. And in two out of his four full seasons he has posted HR/FB rates below 6.5%. His home park does suppress home runs, but not to such an extreme degree. Without any real explanation for how he is accomplishing his prevention of both hits on balls in play and homers on fly balls, we cannot be sure how long those apparent skills will last.
Zimmermann seems to be a safe bet, but he’s precisely the type of pitcher that will rarely, if ever, appear on my fantasy teams. His strikeout rate surge looks to be a bit of a mirage and I would rather bet on a pitcher maintaining a strong skill set than a low BABIP and HR/FB rate.
Mike Podhorzer is the founder of ProjectingX IQ, an advanced fantasy baseball analytics platform that transforms projection data and in-season performance signals into actionable intelligence. He is the 2015 Fantasy Sports Writers Association Baseball Writer of the Year and three-time Tout Wars champion. He is the author of the eBook Projecting X 2.0: How to Forecast Baseball Player Performance, which teaches you how to project players yourself. Follow Mike on X@MikePodhorzer and contact him via email.
Swinging strike percentage is a statistic with a lot of samples. Wouldn’t that make it a good indicator of a change in fastball quality? The movement on the fastball also changed, and perhaps there are sequencing effects with his new slider that are showing up in his fastball numbers. I generally believe any per-pitch change in statistics.
Agreed with other Matt. Also we do see real change. As Eno has been bringing up lately, pitching up in the zone can get effective with the fastball, especially when you can get them to move eye levels
Year to Year: http://tinyurl.com/ngv3hln
2014: http://tinyurl.com/mk2jnvh
2011-2013:http://tinyurl.com/ny9756j
You need to dig a bit deeper. Call for regression without digging into the Pitch F/X stuff is a mistake in my opinion because these things like the above commentator said, do tend to stabilize quickly/
The analysis on Fangraphs, apart from the main guys (Dave, Jeff, Eno, etc.), has been really lazy lately. It’s disappointing.
I’m not sure why pitcher up in the zone more frequently this year weighs so much more heavily than his previous seasons. It’s just like any other metric. We still need to assume regression toward career levels. Just because he did it one year doesn’t necessarily mean he will the next.
Bottom line is that throwing 70% fastball doesn’t typically result in very good strikeout rates.
so then you would agree that jon lester is going to regress back to his chicken and beer form, right? because i remember reading an fangraphs article explaining how lester “changed his approach” and thus his reemergence as a front line starter is sustainable. he basically just starting throwing it inside to righties, a tidbit i view as just as predictive as zimmermann’s high fastball usage.
**that would be his usage of fastballs high in the zone, lol, not his high usage of fastballs in general
Should we assume it is just a blip on the radar though? I seem to think a sample size of 2130 pitches of something that probably stabilizes incredibly quickly should be more predictive of the future than data from 2012 or 2013 especially when there is a tangible change in approach. I think it might be a mistake to assume this isn’t an intentional change. As we’ve heard from a couple of the pitchers Eno has spoken to, throwing the fastball up to get whiffs is a something pitcher intentionally do. He traded groundballs for strikeouts.
As for the 70% Fastball part…You know who threw 70% fastballs? Clayton Kershaw in 2010. If he stops using the fastball 70% of the time, he goes to throwing an above average slider or curveball that generate even more whiffs.
hmk, I didn’t say expect complete regression to career levels, but toward career levels. Lester and Zimmermann may very well hold onto most of their gains, but we have a long history of established performance and pitch approach that can’t be ignored. It’s almost always correct to assume some level of regression toward career marks.
Does the second to last paragraph here make anyone else think of Matt Cain. I’m hearing a lot of the same symptoms. Conistantly outperforming his SIERRA/FIP; posting low ERA’s and below average K rates despite having very good control and a fastball with good velocity. The question is, as it was with Cain, when will the other foot drop?
The best i can find is that his K rate vs. RHH dramatically increased in 2014. So i dug deeper…why did it increase vs. RHH so dramatically? The best i could find was that per Brooksbaseball, he increased his fastball usage overall by 4% vs. RHH, and increased usage of the fastball when in the “pitcher ahead” (+7%)and “two strikes” (+6%) situations. So while the fastball in general is a low swgstr% pitch, his fastball generates above avg swgstr%, and thus his K/9 or k% was boosted into a slightly higher than average rate.
Maybe a simple mindset change of challenging hitters with his heater by throwing less of his curveball (which also was below average swgstr% career wise) during the two strike scenario.
I saw a slight regression, but not very much to where he drops back to career averages.