Wednesday, June 28, 2006

Bill Hall Has Crazy Splits

While Bill Hall compiled an impressive .839 OPS in a breakout 2005 season, some (including myself) felt that Hall would be bound to regress a bit in 2006. Instead of regressing, however, Hall has continued where he left off, compiling a .271/.322/.567 line in 247 AB so far this year. While his average and OBP is 20 points lower this year than last, his power has been through the roof. What gives? What is the cause of this improvement?

Surprising, 54 AB has made Bill Hall an All-Star worthy SS this year. Here are his splits by pitcher handedness:

Bill Hall, 2006
            AB   AVG   OBP   SLG   OPS
vs. Left 54 .389 .469 .833 1.302
vs. Right 193 .238 .277 .492 .769
He has absolutely crushed lefties but has actually batted pretty poorly against righties (which make up 75% of his total AB). Those 54 AB against southpaws have been SO good,however, that they end up completely masking the struggles he's had for the majority of his AB.

How atypical of a split does Hall have? Generally, all right handed hitters perform better against left handed pitchers. Here's the league wide split (thanks, Retrosheet) for 2005:

MLB, 2005
          AVG   OBP   SLG
R vs. R .257 .316 .407
R vs. L .272 .341 .435
Adv. .015 .025 .028
An average right handed batter gained .053 to his OPS by facing a lefty, relative to facing a righty, last year. Bill Hall, on the other hand, is currently enjoying a .533 advantage against lefties! Has Hall always had such a huge advantage against lefties? Let's look at his previous 3 seasons:

Bill Hall, 2003-2005
            AB   AVG   OBP   SLG   OPS
vs. Left 257 .261 .327 .432 .759
vs. Right 776 .269 .306 .448 .754
In the past, while he's gotten on base a little bit more against lefties, he's actually shown more power against righties. These splits are also atypical but in the other direction of 2006! How do we make any sense of all this?

These sample sizes simply aren't large enough to reveal Hall's true ability vs. left and right handed pitchers. "The Book" concluded that a batter needs something like 2,000 AB before his personal lefty/righty splits are more statistically significant than league average splits. I'm not saying that Hall is bound to regress to league average (I'm not being fooled again!) but some kind of adjustment is in order. Either his OPS against lefties is going down or his OPS against righties is going up but something is going to close that gap.


Anonymous Rob said...

Well Hall isn't that good agaisnt LH pitchers and better than a .230 agisnt RH pitchers. So his numbers will fall aginst lefties to good degree and rise against RH pitching. Truthfully this is not that surprising, you can find 50 ABs anywhere that makes a player at this point. Lee's 50 ABs in Houston, LA, and Chicago are making his season.

8:51 PM  
Blogger rluzinski said...

Well, I didn't just choose 50 random AB, though. There's a significance to Hall's excellant 50 AB (vs. lefties), in that they should have a relationship with the rest of his ABs (against righties). Since that relationship is way off, something has to give.

10:34 AM  

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