Following up on my work on balls-in-play from the other day, I noticed that a few Brewers were notably unlucky or lucky compared to their career numbers. Usually that's a sign that they'll bounce back to their averages the following year--not such a good sign for Brady Clark or Geoff Jenkins.

So, first, I wanted to see how extreme the lucky Brewers were, relative to the rest of the league. The following table shows the 28 or so "luckiest" hitters in 2005, based on the difference between their batting average on balls in play (H/BIP) in 2005 and their career average. I limited this study to those with 250+ ABs in '05, and 1300+ ABs in their career, including 2005. You'll have to trust me for the moment, but suffice it to say that these guys are very unlikely to repeat their high H/BIP next year. Here's the list:

Wait just one minute, stat boy.
Now, I can hear people arguing already--how do we know these players are "lucky?" Couldn't they have gained better control over balls in play? Didn't Brady improve his hitting skills? I wondered those same things, and since I clearly like to play with data, I decided to look a bit further into a bit.

The next (and last) table is the same thing, only for players after the 2004 season. Since we know how those players did in 2005, we can see whether any of them maintained their new, higher H/BIP level. So in addition to 2004 and career (up to 2004) H/BIP stats, I also include 2004 and 2005 batting averages:

Bad news for Kenny Lofton fans
In other words, very good BIP luck (relative to the player's career) is more or less unsustainable. Based on this small sample, anyway. (I'm pondering doing this project justice and going back through a few decades of stats--if I do, you'll see it here first.) 29 of the top 30 BIP-luckiest hitters in 2004 saw their batting averages go down in 2005--many of them quite substantially. The only one who didn't--Carlos Guillen--may have established a higher level of skill somehow, but it's far more likely that he just got lucky two years running. His .358 H/BIP in 2005 is among the league leaders, and while he might be expected to maintain a H/BIP above league average, he'll probably come back to earth next year.

The moral of this story is twofold. First, I'm more thrilled than ever that we were never considering signing Kenny Lofton. Second, I'm afraid we should expect slightly less production from Brady Clark and Geoff Jenkins next year--unless, of course, they up their HR or walk totals to offset the likely decrease in H/BIP.

Tomorrow I'll look at the flip side of H/BIP--players who were notably unlucky relative to their career totals in 2004 and 2005. Sneak preview: it's not the mirror image of what I've said above...not even close.