Tuesday, September 1, 2009

Fun with RBI Opportunities

I'm a big fan of the RBI Opportunities Report over at Baseball Prospectus. Sort by OBI% (and enter a minimum number of PA), and it shows you the percentage of runners on base during each hitter's PA that that hitter has driven in. If you want to impress on somebody how completely context-dependent players' RBI totals are, it's really nice to be able to head over there and point out how David DeJesus is doing a considerably better job driving in the runners that have gotten on base for him than Mark Teixeira is, or that Yunel Escobar comes out ahead of Ryan Howard.

But that's not totally fair to the sluggers, is it? I mean, really, a player has one RBI opportunity in each plate appearance that's not accounted for here, because he could always drive himself in, and of course Tex does a much better job of that than DeJesus does. So to get the true percentage of potential RsBI converted, counting the hitter himself as one such potential RBI, we'd have to do this (where "ROB" is the total number of runners on base for the hitter's times at bat, according to the BP report linked above):
RBI / (PA + ROB)
Right? I'm sure this isn't by any means a new idea, but I haven't seen it. I don't have the kind of database I'd need to really do this for everybody (I'm pretty sure I could do something like that, but haven't got around to figuring it out yet), so let's take a look at just a few.

First, the leaders in RBI total in each league (all stats through Sunday):


First of all, note that this is a terrible way to measure the value of anything. It gives a huge advantage to guys who get the most opportunities with runners on base (much less of an advantage than just counting up RBI totals gives them, but still) and punishes guys who get lots of PA without runners on, since your odds of hitting a solo HR are a lot worse than your odds of getting a runner home from third. But anyway, it was just for fun. And as I said, the Baseball Prospectus OBI% method has the opposite problem, so I thought I'd give the HR hitters a bit of a bump.

So. Teixeira is not the best in the American League at driving in runs on a per-opportunity basis. Fielder may be the best in the NL; he's at least the best out of the top 11 in total RBI (note that he also leads the NL in plate appearances, so his dominance of this made-up statistic is especially impressive).

But you know, all those big guys at the top still do a pretty good job by this method. Still, though, to lead the league in RBI seems to take a healthy amount of ability and luck: of the four guys with over 100 RBI as of Sunday, three of them have seen the first (Tex), second (Howard) and sixth (Prince) most runners on base during their PAs. The fourth, of course, is Pujols, who is just 15th in ROB.

Your luckiest, most opportunity-dependent RBI leaders are the guys you'd actually expect...especially Aaron Hill. A lot has been written lately about how Aaron Hill is suddenly this big surprise run producer, and yeah, it's pretty shocking that he's cracked out 31 homers. But with a .322 OBP, he's just a slightly above average hitter (.350 wOBA). He's acquired all those RBI (and to some extent all those HR) by having the most plate appearances in the majors. He's also 8th in the AL in ROB.

Of the 10 RBI leaders in the AL, 6 are in the top 10 in the league in ROB. 8 are in the top 14. Morales and V-Mart are the oddballs (-slash-impressive run producers) at #24 and 48, respectively.

Of the 11 RBI leaders in the NL, 7 are in the top 10 in ROB, and 10 are in the top 17.
Hanley Ramirez is your real Mr. RBI (well, after Fielder), way down at #26.

So, yeah. Next time someone starts talking about a Good RBI Guy, you can correct them--about 90% of the time, he's more of a Lots of RBI Opportunities Guy.

A few more, just for fun:
Mauer.....464.....268.....79...... .1079 (better than all of the above AL guys except Morales).
Jeter.....582.....296.....60.... .0683 (all those leadoff PA make this a useless stat for him).
Utley.....556.....338.....84..... .0939 (if only he could be hitting behind Utley every day).

Okay, that was pointless but fun. Next time, something poignant but mind-explodingly dull.

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