Thursday, August 28, 2008

RBI Opportunity Percentage (RBI%)

I was playing around with a new stat in my head the other day, so I thought I'd flesh it out here. I know I've been beating the "RBIs are useless" drum on the Flushing University message board, so I figured I'd try to find a way to contextualize it.

It's not that RBIs themselves are useless - it's that comparing two players with a counting stat that's dependent on so many other variables is not a good measure of offensive ability. I'm calling it "RBI Opportunity Percentage" - or RBI% for short.

Here's my theory - when runners are on base, the ultimate goal of any subsequent at-bat (except in the event of a sacrifice bunt without a man on third base) is to drive those runners in. It's not fair to look solely at RBIs as a measure of effectiveness, because a player with 300 chances to drive in runs is going to have more RBIs than a player with 200 chances.

So here's what I did: I looked at a player's number of plate appearances with runners on base and their RBI totals in those situations. I subtracted the number of home runs from those RBI totals, because it unfairly benefits the home run hitter to leave them in. (Yes, I know that makes this a somewhat flawed stat right off the bat, so feedback is encouraged.)

Then it's simple: take the rest of the RBIs and divide them by plate appearances. Let the result go three decimal places (so it looks like batting average, on base percentage and sluggng percentage) and you have RBI Opportunity Percentage. I think it's a better measure of ability than RBIs, because it puts everyone on a theoretically equal playing field and rewards the hitter who makes the most of his opportunities.

2 comments:

Deb said...

You know I LOVE this, Jack, but I think in order to fine tune it, you have to find a way to work the home runs into the whole thing somehow. I'm not sure about the statement that home run hitters unfairly benefit by leaving the home runs in, anyway. Why shouldn't they benefit; if they hit a HR with the bases empty, that doesn't show up in your stat, anyway, and if they hit a HR with ducks on the pond, it seems to me that they should benefit, having produced many more runs than going solo, which doesn't show up anyway, and may in fact balance out at the end.

*Sigh* I hate stats, lol.

brian said...

Call it the "David Wright sucks" stat.