The Papelbon Conundrum

I don't know anything about what it takes to be a major-league pitcher. I have spent my life learning to throw a curveball, studying aerodynamics and mechanics and trying to understand how or why a certain thing happens, while also studying to analyze and understand what each of these things mean, but as far as I know, I don't know one iota more than the average baseball fan about how throwing a baseball works. All of that having been said, however, there is one guy I have always felt that I understand, and that is Jonathan Papelbon.

Papelbon, a two-time Baseball America top-100 prospect, came into the league in 2005 as a starting pitcher with the Red Sox. A successful stint as a setup man late in that season, combined with an absolutely dominant performance as the closer in 2006 convinced the Red Sox to keep him in that role, and over the duration of his career has been the most dominant relief pitcher in the major leagues.

As a young Red Sox fan, Papelbon was the first guy who showed me what an 'explosive' fastball was, and the value of a live fastball that you can command. After his minor shoulder injury he taught me about pitching form and basic mechanics -- and his are very good. After a strength program, he's been perhaps the most healthy relief pitcher in baseball since 2006, with not so much as a day of soreness or dead arm on his record. What I'm trying to say here is that Papelbon may be the one pitcher that I've felt that I really understand.

Sometime in 2009 I watched a Mythbusters episode about baseball, and one of the things they addressed was whether or not a curveball curves, and they magnificently demonstrated that (and how) it does by visiting NASA's Ames laboratory in San Fransisco. In this video the aerodynamic principles around a curveball are displayed beautifully: the forward spin disrupts the air beneath it, creating a vacuum, while building up something of a head of air above it, which effectively pushes the ball downward. The opposite effect, which Roger Clemens explains here, can be applied to a four-seam fastball. The air above the ball is disrupted, while a pocket of higher pressure is created below the ball, which creates a ball that, in effect, falls slower than it should. In this video, the NASA guys explain that an elite MLB pitcher can create enough backspin to actually negate half the weight of the ball, essentially suspending it during its vertical journey.

What makes Papelbon so good is this backspin. Yes, he throws a decent splitter and something resembling a slider, and yes he features upper-mid-90s heat, and superior command of the fastball, but the 'upward', explosive movement of his four-seamer is what sets him apart. Since 2006, he has ranked among the top pitchers in baseball in this category. If you watch his awesome delivery, you can see how much he gets under and behind the ball to create this spin.

Three years into his major league career, as he was taking the mantle from Mo Rivera as the preeminent closer in baseball, something happened. He added a slider. He played with a cutter. He's never said as much, but I suspect that these things played with his delivery. His perfect delivery. In any case, something changed, and he stopped getting behind the ball like he did from 2005-2008. He got wider in his delivery, the ball came from the side more, adding lateral run, like a two-seamer, and his horizontal movement increased.

The effects were noticeable in 2009 and 2010. The ball moved more laterally, less vertically. Where it would once charge into the upper corners of the zone and hop over bats, it now leaked into the heart of the plate, or outside of the zone altogether. He missed fewer bats, he walked more guys. The effects on his production were obvious, as 2009 and 2010 were without doubt the worst years of his career.

These are just my observations, or at least they were. I never looked at the numbers or tried to confirm my theories. But watching the Phillies game Monday, in which Jonathan Papelbon threw a running, lateral fastball to Austin Kearns, who hit it out of the park, made me think back to these theories and I decided to apply the math to them. This is every season from 2007-2011, with Papelbon's SIERA and X Movement (horizontal movement):



SIERA is the most comprehensive pitching metric we have, but for the purposes of this conversation, all you need to know is that higher = worse, just like ERA. What this graph shows is a direct correlation between Papelbon's SIERA and the horizontal movement of his fastball. Way back in 2009, Dave Cameron at FanGraphs analyzed the correlation between fastball velocity and strikeout rate and found what he called a notable correlation with an r-squared coefficient of .229. In the above comparison, the chart features an r-squared of .385. I probably don't have to say that this is a direct and significant correlation.

The genesis of this post, and its conclusions, are the result of me watching a sloppy pitch from a very good reliever to a mediocre hitter sneak over the wall at a homer-friendly ballpark. I'm not saying Papelbon has lost his release point or his delivery, or whatever the problem was in 2009 and 2010, and I'm certainly not saying that I know why those things happened or how to correct them. But, this was an interesting tidbit in Papelbon's history, and something to watch for as he goes forward in a possible six-year deal with Philadelphia.