B.J. Upton Overload: A Hypothesis and a Look at Upton's Balls in Play

To those of you that don't like it when we drag a subject out, I'm sorry in advance. There were lots of words spilled on BJ Upton yesterday, with a FanPost by Transplanted, an article by Tommy, and an article by Dave Cameron over at FanGraphs. For those of you that didn't get a chance to read all those excellent articles, let me summarize them for you:

• Transplanted: All of BJ's major statistics have been trending downward over the past three years, and now his plate discipline seems like it's going as well. He needs to make more contact by "fixing his swing mechanics and recognizing pitches better."
• Tommy: Upton has gotten slightly unlucky with Balls in Play, meaning his average should be higher than it is, but the biggest problem with him is that he's swinging and missing waaaaay too much, especially on four-seam fastballs. Although we'll need to get the advice of a professional to know for sure, it seems likely that something is wrong with Upton's swing. 
• Cameron: Abort, abort! Upton has a poor plate approach and he chases pitches outside of the zone. TRADE HIM NOW!

One of these things is not like the other. True, I've exaggerated Cameron's point a lot - and for the record, I'm a huge Dave Cameron fan and it's nice to hear an opinion on Upton from an emotionally-unattached fan. Maybe our fandom is blinding us and the Rays are stupid not to trade Upton at this point; you can certainly make an argument for trading him.

However, while I'm sure the Rays' front office is considering every option, I disagree that this is something the Rays will or should do. If the Rays had reason to believe that Upton is a true-talent .210/.285/.370 hitter, then yes, the Rays should trade him while his value is still somewhat high and bring up Desmond Jennings. Cameron's idea hinges on the belief that this Upton, the one with the hole in his swing and the .301 Weighted On-Base Average (wOBA), is who we're getting for the season. Upton's getting expensive and if he's not going to hit, the Rays should cut bait.

And that's where I disagree with Cameron: I do think Upton's going to hit this season. After the jump, find out why.

In case you forgot, here's how Upton performed in April:

Pretty great, huh? But then things spiraled down into chaos in May:

What happened? After looking so good, why did Upton's numbers go to hell all of a sudden? Which Upton are we going to get going forward - the one that looked like he had put everything together, or the one that is striking out in 40% of his at bats?

After looking over Upton's balls in play data (at the suggestion of EminenceFront) and re-reading Tommy's article, I've come up with a hypothesis: Upton started off the year great, driving balls to the opposite field and flashing real power again, but then the pitchers adjusted to him. They realized that leaving the ball on the outside part of the plate was asking for trouble, so they've started pounding Upton inside with four-seam fastballs, daring him to turn on a pitch and make them pay. And at the moment, Upton can't.

Here's a graph of Upton's wOBA over the past four seasons, broken down by where he hit the ball:

As you can see, last season Upton could pull the ball but put couldn't push the ball; this season, it's the exact opposite. Upton has never struggled with pulling the ball, even when his shoulder was lousy, so I find it hard to believe that he's lost the skill entirely in one year. It could simply be that with all the work this off-season, Upton focused very highly on going the opposite way, to the point where he over-prepared and didn't work on pulling the ball enough. Or maybe Upton is simply having problems adjusting his swing to having a healthy shoulder, so he'll need to keep tinkering and working on his swing continuously as the season goes on.

Whatever the reason, though, Upton needs to show he can turn on a fastball and pull it to left field instead of just swinging through it. My hypothesis is that the hole in his swing is on the inside part of the plate, and it's keeping him from being as dangerous a hitter as he could be. If that's the case, it seems like it's a fixable problem and Upton should be able to adjust. I don't have the data to prove if he's seen more or less inside pitches in May, though, so my hypothesis may be entirely wrong. Maybe Upton's bat has slowed down and he can't turn on fastballs anymore, which would be a much more serious problem. Or maybe the lack of pulling the ball has nothing to do with the hole in his swing. 

In the end, I believe that once we see Upton turn on a ball with authority, we'll know he's closing that hole and we've got the full Bossman back. I think he can do it, but then again I'm obviously biased. And if the Rays believe that they won't be able to fix Upton's current problem - whether it be a hole in the swing, bat speed, or whatever - then by all means Mr. Cameron, we should think about trading him.