Monday, April 1, 2013

RBI--A Matter of Opportunity

To begin, a technical point that only a junior high newspaper editor (which I most certainly WAS NOT, since I was much cooler--a debater) could love. You see the title of my post and say to yourself "Hey, that should be RBIs because it's a plural. I'm gonna tweet that guy and tell him he's an idiot and SHOW HIM!" Easy there, big shooter. If a hitter drives in one runner, he has a run batted in. If he drives in two runners, he has two RUNS batted in, not two run batted INS or two runs batted ins. Kudos to BIll James and his New Historical Abstract for pointing that out to me in only my fourth reading of the book.
The notion is as old as baseball that the RBI producer is an essential element of any successful team, with runs scored taking a secondary status. Bill James states it succinctly in his 998-page New Historical Abstract (2001, p545):

Baseball writers have always overrated RBI, and ignored the fact that runs scored are essentially a function of men on base. (emphasis and highlighting added)

This table shows how many base runners are driven in by base situation. To explain:
In 1950, 5.0% of runners on 1st scored in a given at-bat, with the range of the 16 teams from 3.7-6.7%

There is a very strong correlation between the number of base runners and winning, for the very simple fact that even with the same percentages, the greater the number of opportunities, the runs scored. Bill James was able to summarize in TEN WORDS (the ones highlighted) an idea that shouldn’t be that difficult to grasp, yet it still happens.

These are the 2012 top 10 in terms of base runners when at bat (BR=base runners, BRs=base runners scored):

This gets to the heart of why I didn’t think that Miguel Cabrera winning the MVP was necessarily wrong. He had a great number of opportunities to drive in runners, a key requirement for leading a league in RBI, but he wasn’t far and away leading the league in opportunities. Hunter Pence had 61 more chances to drive in runs than Cabrera and ended up with 35 fewer RBI (139-104). 

The next table shows the leaders (minimum 300 AB) in percent of base runners scored when at bat:

Cabrera wasn’t even the leader in 2012, but his 22.2% of base runners scored is pretty darn high. When the MLB average was 14.5% (fairly stable over time), anyone who drive in runners 50% over the league average not only has the opportunities, but takes advantage of them.

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