Mike Pelfrey's Lost Sinkerball Season

by Chris McShane on Feb 23, 2011 2:01 PM EST

Although he lived up to his reputation as a groundball pitcher in 2010, Mike Pelfrey didn't throw his sinkerball anywhere near as often as he might have hoped. According to Andy McCullough, Pelfrey felt the pitch had little to no movement, casuing him to rely heavily upon his four-seam fastball. McCullough notes that Pelfrey twice before experienced a season without the pitch, once in high school and once in college.

The data from Pitchf/x can be a little tricky, as it differentiated between a two-seam fastball and sinker in the 2010 season. The data says Pelfrey used a sinker 15.6% of the time while using the two-seam fastball an additional 12.5% of the time. Although the two pitches are really the same one, the system picked up on a difference in vertical movement, classifying the ones with more movement as sinkers and the rest as two-seam fastballs. Pitchf/x seems to have noticed the same thing that Pelfrey did from the early stages of last season: the sinker wasn't working.

It's well-known that Pelfrey had a pretty good year in 2010 but struggled mightily in the month of July. Turns out that's the same month in which he most frequently threw the sinker. Correlation doesn't equal causation, but the relationship between the percentage of sinkers he threw and his overall performance is worth noting. (Note: In the graph below, the percentage of sinkers has been divided by ten so that it's on the same scale as his FIP.)

Pelfrey's performance was generally inversely proportional to how often he threw the sinker, which is an odd phenomenon for a guy who thrives on generating groundballs. Unfortunately, it's difficult to compare the pitch to seasons prior to 2010 since Pitchf/x barely made note of either the sinker or the two-seam fastball before last year. The data from last season does demonstrate that Pelfrey's sinker wasn't getting him the results he normally expects.

Dan Warthen and Pelfrey say that bringing back the sinker and reducing the reliance upon the four-seam fastball is big part of what he hopes to do in 2011. Despite his ineffectiveness with the pitch last season, Pelfrey still ended the year with a 47.8% groundball rate. That's good, but it was down from the year before and nearly two percentage points lower than his career average.

There are many factors that will determine how Mike Pelfrey fares in 2011, but the re-emergence of his sinker would likely result in a better 2011. The fact that last year went as well as it did without the sinker should give Mets fans reason to be optimistic. If his sinker returns and he maintains his normal strikeout and walk rates, Mike Pelfrey could outperform his 2008 and 2010 seasons. Mets fans would gladly sign up for that.

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I don't want him to maintain his career K rates

I want him to improve on them!

"Blinding ignorance does mislead us. O! Wretched mortals, open your eyes!"
Gil Hodges IS a Hall of Famer.

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by Brooklyn Dodgers Mets Fan on Feb 23, 2011 2:38 PM EST via mobile reply actions

I'm not sure if FIP is the best indicator for the sinkerball

as it’s not really meant to be a strikeout pitch, it’s supposed to be put in play with weak contact most of the time. Using the sinkerball more is going to reduce his K rate. Even if his BB and HR rate stay the same, the reduction in K’s alone could cause the FIP difference.

Hey, wait! I'm having one of those things. You know? A headache with pictures?

by KeithsMoustache on Feb 23, 2011 2:39 PM EST reply actions

His ERA was awful in July, too.

by Chris McShane on Feb 23, 2011 3:22 PM EST up reply actions

true, just commenting i'm not sure the connection between FIP and sinker was the best comparison

not saying he wasn’t abysmal in that month. Is it possible to get pitch run value breakdowns by month? That would be interesting.

Hey, wait! I'm having one of those things. You know? A headache with pictures?

by KeithsMoustache on Feb 23, 2011 5:12 PM EST up reply actions

and yes i know this would be subject to the SSS demon, but still might be interesting to see

Hey, wait! I'm having one of those things. You know? A headache with pictures?

by KeithsMoustache on Feb 23, 2011 5:13 PM EST up reply actions

In my observation

You can tell in the first two innings whether Pelfrey will be any good. It all comes down to swinging strikes for him. I don’t have batted ball stats, but I would bet money that Pelfrey’s swing and miss percentage was way down in July, possibly the symptom of a “flat” sinker.

by goquakers on Feb 23, 2011 2:51 PM EST reply actions

Correlation doesn't equal causation

But it doesn’t not equal it either. And it matches with what Pelfrey himself observed. My question is..Why did he keep doing it?!?!

I mean…My sinker is not working. I’m not getting guys out. Maybe if I throw my sinker more. Oh look, I’m not getting guys out. More sinker? This was one of my complaints about Warthen btw, is that he was/is slow to notice and fix problems.

It probably stands to reason that Pelfrey was throwing more sinkers because he wasn’t throwing it well and generating baserunners which prompted him to want to throw the sinker to get a double play, but instead he got more baserunners, which prompted him to want to throw the sinker to get a double play, but instead he got more baserunners, which prompted him to want to throw the sinker to get a double play, but instead he got more baserunners, which prompted him to want to throw the sinker to get a double play, but instead he got more baserunners, which prompted him to want to throw the sinker to get a double play, but instead he got more baserunners, which prompted him to want to throw the sinker to get a double play,

sorry, is it August yet?

-Ceetar, the Optimistic Mets Fan

by Ceetar on Feb 23, 2011 4:47 PM EST reply actions

I’ m not as crazy on Pelf as others. His career FIP versus lefties is underwhelming (4.83), though it did improve some last year (4.54), probably due to the splitter and improved secondaries. He also has pretty significant home/road splits for his career (3.76 FIP at home, 4.77 on the road), mostly due to a large gap in HR/FB rate: 5.2% at home, 9.9% on the road, both of which are still under the expected 10.6ish marker (if you believe homeruns are luck and not really a skill, that is). So, in other words, without Citi, Pelf is probably more like a back of the rotation arm than a very good #3-type starter. Fortunately he has Citi to lean on, and hopefully his HR/FB luck (or skill?) both at home and on the road continue so that he looks better than he might really be.

by nmigliore on Feb 23, 2011 8:15 PM EST reply actions

It was his mechanics

Pelfrey had a sporadic issue of hunching over at the balance point, which caused his upper body momentum to move slightly toward 3B and then toward 1B — more of a horizontal momentum rather than vertical. In turn this caused his arm to move similarly, and it changed his release to be a touch more side-to-side instead of from “on top”, and thus his fingers slid just a hair to the side of the ball on release and caused his fastball to move with more sideways movement than sink. With less sink you get less ground balls, theoretically.

It only takes a few millimeters of difference in the release to cause a significant change in ball movement. There are some pics to see the subtle “hunch over” issue here:
http://www.metstoday.com/4874/pitching-mechanics/a-stiff-neck-could-be-good-for-pelfrey/

by joejanish on Feb 24, 2011 12:49 AM EST reply actions