Ben Bernanke and the ERA

I know precious little about monetary policy. But I am inclined to enthusiasm about Ben Bernanke’s nomination to replace Alan Greenspan after hearing this on NPR about what might be called the “Bernanke-Jaffee Theory” on baseball’s hallowed “earned run average.”

The ERA is a measure of the average number of runs a baseball pitcher would be expected to give up over a full nine inning game. It’s is calculated based on the number of runners a pitcher allows to reach base who eventually score. The rub, as Bernanke and former Princeton colleague Dwight Jaffee came to undertand, involves runners who reach base on a pitcher’s watch, but only score later after a relief pitcher has entered the game.

The run is charged to the first pitcher, and the second pitcher gets off scot-free. Yet it took both events for the run to score. The result is that relief pitchers tend to have artificially lower ERA’s, as measured by their actual contribution to runs being scored, while the starting pitchers’ ERA’s are artificially higher, as Jaffee explained in the NPR interview.

This is a reverse manifestation of another inefficiency in the baseball marketplace that has always annoyed me – the obsession with the Run Batted In. When a player gets a hit that allows a player already on base to score, he is credited with a Run Batted in. This is the manliest of baseball statistics – a high RBI total. Yet two discreet acts are required for this to happen, and the first, the guy who got in base in order to be driven in, receives little credit in the hagiography of baseball commentary. Their contribution to this total can be measured in simple runs scored, yet one almost never hears baseball announcers waxing poetic about a players’ runs scored total over the previous season.

The wacky Sabermetricians (baseball statistics junkies) have come up with all sorts of variants of a statistic called “runs created” (see here for a discussion) to try to come up with a more meaningful number. I don’t pretend to understand them any more than I understand monetary policy. I just try to keep track of how many runs a player has scored. It’s a reasonable measure. But I fear we’re stuck with the ERA.