Should the Pirates platoon Garrett Jones and Steve Pearce?

Matt Klaasen, formerly known as Devil Fingers, wrote an excellent post the other day on platoon splits. Essentially, Matt cautioned against treating platoon splits as a clear-cut skill and encouraged the use of regression when projecting future statistical splits. I do not have the statistics acumen of a Fingers or a Tango, so I generally avoid getting into regression and the like. But in this case, Matt has already taken care of most of the work. So I decided to apply his formula to a Pirates-related situation.

I have been interested in a platoon of Steve Pearce and Garrett Jones, whether that is at first base or right field. This is mostly due to their 2009 splits, which is the precise assumption that Matt was cautioning against. So let’s see what we can expect from Pearce and Jones in 2010. First, here are their career splits.

Let’s look at one of Matt’s examples and the methodology he used.

We’ll begin with everyone’s favorite example of a “big splits” guy: Curtis Granderson. For his career, Granderson is a .358 wOBA hitter. However, while he has hit a robust .380 vs. RHP, in 685 versus LHP, he’s been 2009 Yuniesky Betancourt with a .270 wOBA. That’s a whopping 110 points of wOBA difference, about 30.7% in observed performance.

But remember — skill is closer to average than it appears. Regressing Granderson’s 685 PA of 30.7% against 1000 PA of league average (8.6%) — (.307*685+.086*1000)/(685+1000) — we get an estimated platoon skill of 17.6%. “Centering” the split is a bit of a challenge, but I weighted it by the number of PAs the player has against LHP in his career (for Granderson, about 23.7%). For Granderson’s split, then, I have +4.2% vs. RHP, and -13.4% vs. LHP. Applying this to his 2010 CHONE projection of .359 wOBA, we’d forecast his 2010 wOBA against RHP as .374, and against LHP as .311.

CHONE projects a .346 wOBA for Jones and a .334 wOBA for Pearce in 2010. Plugging our own numbers into Matt’s formula, we get the following projected splits.

Judging by these calculations, the Pirates should expect a small advantage if they effectively platooned Pearce and Jones in the upcoming season. But that benefit is not nearly as dramatic as each player’s career numbers would indicate. Both players have a limited number of career plate appearances, so that advantage may become more distinct down the road if they are able to continue this early trend. There are reasons to think that may happen. Jones has a history of struggling against southpaws in the minor leagues, with far better numbers against right-handers. Pearce’s minor league split has historically been smaller, but he has had difficulty with upper-level off-speed stuff, which could enhance the gap.

It might be a bit early to try a Pearce/Jones platoon this season. But if their early major league trends continue throughout the year, the Pirates should consider the idea for 2011.