# Carleton: Believing in clutch hitting

From Russell Carleton at Baseball Prospectus on August 12, 2014:

I know, I’m not supposed to, but I believe in clutch hitting.

By clutch hitting, I mean that certain players have some sort of ability to perform better in higher leverage situations. Leverage, for the uninitiated, is a concept formalized by sabermetrician Tom Tango. We know that some situations in a game are more important than others. When it’s 15-1, no one cares what happens in a plate appearance. When it’s the bottom of the ninth with runners on second and third, two outs, and the home team is down by one, pretty much the entire game rides on this at-bat. Leverage index is a mathematical model of how much more important that late game situation is.

Leverage is based on the idea of win probability. We can look at each game situation (let’s say, bottom of the third, one out, runner on first, and the home team down by two) and figure out over some past time frame how often the home and visiting team won. More to the point, we can figure out how much that win probability can change based on whatever is about to happen next. In the 15-1 situation, whatever the batter does is going to move the needle very little. In the bottom of the ninth, the win probability could go from roughly 50–50 to 100–0 in a hurry. When a batter does something positive that increases his team’s chances of winning, we give him credit for adding win probability (even if giving him all the credit is silly). In a high-leverage situation, a batter can accumulate a lot of win probability in a single at-bat.

The standard test for whether there is such a thing as clutch hitting has been to look at the win probability that a player records over the course of a season and compare it to what his win probability would have been in situations where the leverage index was 1. (This is the basis of how our friends at FanGraphs calculate clutch.) From season to season, players show very little correlation on this measure of clutch. In general, the interpretation has been “clutch doesn’t exist” rather than “we had a poor measure of clutch to begin with.” Indeed, I have found that this measure of clutch eventually does become reliable. It just takes a while. Maybe there is signal in all that noise; maybe we need a better antenna.