Sunday, February 01, 2009


Eugene Freedman wrote:
According to the new BIPAvg research from the Hardball Times, (Mike) Aviles was the luckiest player last year in terms of reverse defensive efficiency. The drop in batting average is inevitable. If he declines elsewhere, the drop off will be significant.
I'm not familiar with BIPAvg, but I'm assuming it's similar with BABIP, or Batting Average on Balls in Play. I'm assuming the vast majority of my readers know what this is, but I've provided a link to the definition just in case.

I don't doubt the importance of BABIP, but I would like to see more data surrounding the assumption that a player is going to regress to the mean one way or the other. Like a lot of sabermetric numbers, this is one where its proponents talk about it like it's sacrosanct without providing any kind of evidence to back up whether or not it's true.

Top 10 BABIP 2007 (Min 440 PA)
1Chone Figgins
2B.J. Upton
3Ichiro Suzuki
4Jorge Posada
5Maggli0 Ordonez
6Matt Holliday
7Hunter Pence
8Edgar Renteria
9Carl Crawford
10Marlon Byrd



These hitters all regressed in 2008. But they weren't all disappointments in Rotisserie terms.

I'd characterize Figgins, Ordonez and Renteria as the non-injury disappointments: players who didn't get hurt but still managed to fall off significantly from previous levels. Yet not one of these hitters made the Top 10 Losses list in the A.L. in 2008.

Renteria ($20 average salary) and Figgins ($29) were discounted from what they earned in 2007. In Figgins' case, this is especially odd given his earnings - $40, $31, $32 - from 2005-2007. The market was actually so suspicious about Ordonez that they insited on a profit from a guy who had earned $42 the year before, paying only $25 for him. So it seems like we're intuitively aware that these hitters are due for a fall whether we follow BABIP or not.

The injury disappointments were Crawford and Posada, and they're a large part of the reason that these hitters lose such a big chunk of change from 2007 to 2008. Posada's probably a poster boy for using BABIP. His rate in 2007 was wildy divergent from his career norms, and his batting average spike was thus unsustainable.

So far, I'm fairly impressed. But that's just one year.

Top 10 BABIP 2006 (Min 440 PA)
1Derek Jeter
2Miguel Cabrera
3Bobby Abreu
4Freddy Sanchez
5Joe Mauer
6Ronny Paulino
7Reed Johnson
8Robinson Cano
9Ryan Howard
10Andre Ethier



What really jumps out at me isn't the regression for these hitters from 2006 to 2007, but how that regression either maintained or worsened for most of these hitters.

Jeter, Sanchez, Paulino, Cano, and Howard all either stayed at their 2007 levels or got worse. Injuries and/or decline surely have something to do with that, but Roto players looking at earnings from year to year instead of BABIP are doing themselves a disservice.

Even Mauer - who bounced back in 2008 - only earned $22. I'd guess a $27 season for him is likely not going to happen again unless he has another fluky BABIP year.

Top 10 BABIP 2005 (Min 440 PA)
1Miguel Cabrera
2Michael Young
3Jason Bay
4Derek Jeter
5Geoff Jenkins
6Adam Kennedy
7Todd Helton
8Jhonny Peralta
9Alex Rodriguez
10Derrek Lee



Uh oh. Seeing Cabrera and Jeter on this list makes me nervous. Isn't BABIP mostly a product of luck?

That's always been where I've been queasiest on BABP. I think a lot of it is luck, but also think there are hitters with better swings who have a chance of getting better outcomes on balls hit in the field of play.

Jeter has a lifetime 361 BABIP. Maybe he's the luckiest hitter who ever lived, but I suspect there's more to it than that. We have less of a sample size to look at with Cabrera, but his lifetime BABIP is .350. The .316 he put up last year might be the fluke, and his backers might be right; a monster year might well be in the offing in '09.

Still, you see guys on the '05 chart (Jenkins and Kennedy) who confirm that there are guys with great BABIP numbers who aren't great hitters, were probably lucky, and are unlikely to sustain it.

Top 10 BABIP 2004 (Min 440 PA)
1Ichiro Suzuki
2Ivan Rodriguez
3Melvin Mora
4Jason Varitek
5Erubiel Durazo
6Mark Bellhorn
7Lyle Overbay
8Todd Helton
9Travis Hafner
10Alex Rios



Suzuki's another guy where you probably want to ignore the high BABIP's (lifetime .356 BABIP) as any indication of a fluke. A .401 is clearly a fluke, but Suzuki's a great hitter. It's not a shock to see him manage to do it.

Durazo and Bellhorn, on the other hand, are surprises. It's funny that we only see the BABIP numbers in retrospect; a number of respected names in both the Rotisserie and sabermetric communities put their necks on the line for these two, despite the fact that their performance wasn't sustainable.

So what do you think?

I think there's definitely something to this (though I again wish that the sabermetricians would go to the trouble of putting something together like this for us instead of just acting like it's obvious). The hitters I'd look out for are the guys who have no sustained record of a high BA/hitting performance. I'd expect them to come down to Earth.

Mike Aviles definitely fits that bill in 2009.

1 comment:

Brett said...

I'm not nearly as up on the latest research as I should be, but as far as I know, the current thought is that pitchers regress to a standard mean, where hitters tend to regress to their own mean.

What exactly contributes to that isn't known, but speed is a major component, which is why you see guys like Ichiro, Jeter, etc. consistently posting higher BABIPs.

I forget where I saw it, but there was just a study done which ran a regression on many different variables and tried to predict a hitter's BABIP. I'll post it if I can find it...