The other side of the coin: bad luck?

Yesterday, I wrote about those players who saw their Batting Average on Balls in Play (BABIP, I was brain-lapsedly calling it H/BIP) spike last year. The guys who had a few years under their belts, yet somehow did much better in 2005 when they made contact and didn't send the ball out of the park.

I claimed (and provided some evidence from a similar group of players from 2004) that those players' boosts were mostly due to luck, and most if not all of their gains would recede next year. The obvious next question is this: what about players who underperformed their career BABIP--will they bounce back? Should you pick them in round three of your fantasy draft?

Proceed with caution.
If you do bet your fantasy league entry fee on a few low-BABIP guys rebounding, you may luck out, but you'll need a deep bench. Unlike yesterday's list, which was filled with players who appeared to have breakout or rebound seasons in 2005, the flip side is quite a bit more varied:

Is this Brian Sabean's Dream Team?
There's a common thread running through much of this list: old, slow, or fading. For a few reasons, this makes intuitive sense. While much of BABIP is due to luck, and it seems unlikely that a player could substantially improve his BABIP, it's unquestionable that players eventually decline. As they do, we notice that their big swings result in 340-foot outs instead of doubles against the wall...pop-ups instead of home runs...fewer infield singles...you can probably think of a half-dozen more symptoms. All of these things show up in BABIP.

So, it seems likely that some of the players on the list (at least five of the top six, for starters) will not rebound. They've gotten a bit less powerful, quite a bit slower, and probably will never see the bright side of a .290 BABIP again. However, there are some names on that list that seem equally plausible as rebound candidates: Corey Patterson, whose horrible '05 may have been somewhat due to bad BABIP luck; Manny Ramirez and Ichiro, both tremendous players who had down-BABIP years; maybe even 2005 disappointments Cristian Guzman and Mike Lowell.

For some insight, let's look at what the same list would've told us last offseason, and how those players ended up performing in '05:

It's an interesting group, headlined by an enigmatic guy to predict, Jason Giambi. Setting aside Giambi, whose horrible 04 season was some combination of decline, drugs, and bad luck, you have the same mix of aging players in their decline phase and possible rebound candidates.

What to make of all these numbers?
One of the toughest things to predict about a player is when they're legitimately declining, and when they just had an off-year. It's possible, however, that we can identify low-BABIP guys like these who are primed for a rebound. It's pretty simple, actually--we want to sort out the guys who are probably declining, and most players start to decline in their early thirties. Let's limit the list to only those players whose playing age in a given season is 32 or under. Here's the 04 list, with 2005 batting average as well:

It's not a slam-dunk case, but it does suggest that younger players who had a BABIP off-year are quite likely to come back stronger the following year. There's reason to be skeptical of low-average sluggers like Hidalgo and Fullmer, but glancing through the rest of the list, you see far more players on the brink of comeback seasons than those who continued to decline at a relatively early age.

Tell me who to pick in my fantasy draft, already, darnit!
Unfortunately, much of this material is scratching the surface. I haven't yet incorporated park factors, I haven't broken down the list of players by type (slow slugger, single-hitting speedster, etc.), and there's a whole nuther world of aging trends I could be examining. But with all those caveats, it would appear that young (defined here as 32 or younger) players who had a BABIP off-year are much more likely than not to bounce back the following year. With that in mind, here's the list of such players from last year:

Time will tell, I suppose. Many of these guys don't inspire too much confidence going into 2006--after all, even if they rebound to their career averages, their 30 point boost may only translate to 20 points in batting average, and the typical decline with age may wash away some of that. Stats like these may be at their best as an aid to common sense, as we could be pretty sure even without looking at BABIP that Mike Lowell and Juan Pierre are in for something of a rebound. But common sense goes both ways: I'd want my team--fantasy or real--to stay away from Richard Hidalgo.