6-4-2 — an Angels/Dodgers double play blog: It's A Myth That Home Runs Come In Bunches

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Friday, May 04, 2012

It's A Myth That Home Runs Come In Bunches — But Don't Tell Pujols

Interesting article by Baseball Prospectus' Ben Lindbergh in ESPN's Insider (paywall) section about how the widely accepted belief that "home runs come in bunches" is actually false:

Using a statistical concept called binomial distribution, we determined the theoretical rates of zero-, one-, two-, three- and four-homer games for the average major league batter. By comparing those predicted rates to how often those games actually occurred, we could see whether there was anything to the idea that home runs are hit in bunches. If players actually alternate between home run hot streaks and dry spells, their long balls would be bunched together, and we would see higher rates of two- and zero-homer games and lower rates of one-homer games than predicted.

Cutting to the chase, the net result of this is that for prolific home run hitters (we don't worry about guys hitting in single digits annually), there may be a "slight tendency to be 'bunched'" (as for Vladimir Guerrero), "but even in his case, it's likely that the difference was due to chance."

So why do Pujols and so many other players mistakenly believe that they're hitting home runs in bunches? A cognitive bias called the "availability heuristic" might be to blame. According to Amos Tversky and Daniel Kahneman, the psychologists who coined the term, the availability heuristic is our "tendency to make a judgment about the frequency of an event based on how easy it is to recall similar instances."

But, Lindbergh concludes, it's probably best not to tell Pujols about this. "One of the most important qualities for a hitter to have is confidence, and the "bunches" belief provides a confidence boost for any occasion." And at this point, having changed leagues and in the first weeks of a very, very long-term contract, it's certain that Pujols needs all the confidence he can muster.

Related: Interesting post about how Pujols' drought mirrors Dave Winfield's in the Bronx. Arte Moreno isn't a jerk, which should at least make the whole process easier.

Labels: angels, sabermetrics