Player Volatility Part I | Part II | Part III | Part IV | Part V
In my last post on Volatility I presented some initial findings about what seems to determine the difference between hitters of similar ability/production and their degree of consistency. If you have two players with similar yearly wOBA's, their Volatility will vary based on their K%, BB%, and ISO.
For folks that would like to play along at home, I've created a quick calculator that allows you to input a player's wOBA, ISO, K%, and BB% and see what their predicted Volatility score is.
You can compare two players at the same time. Remember, since wOBA has by far the largest affect on Volatility it's more helpful to compare players of with wOBA totals that are very, very close.
Here's one example of where this can be interesting: Whose been less volatile this year, Jacoby Ellsbury or Curtis Granderson?
Elsbury currently as a wOBA of .396 and Granderson .397. From an overall production standpoint, they have been dead even. If we plug their statistics into the Volatility Calculator, however, we see that Elsbury is expected to be the less volatile hitter compared to Granderson.
Elsbury has a lower K% and a lower ISO. The previous analysis showed an interesting relationship between ISO and Volatile, in that players with really high ISO's were more likely to be more volatile in their day-in, day-out performance than those with relatively lower ISO's. The idea wasn't that hitters should strive for ISO's <=.100, but rather higher ISO hitters were more likely to be boom or bust-type hitters and unlikely to perform on a consistent basis.This is, of course, just an estimation. It doesn't mean that Ellsbury has been the less volatile hitter this year in actuality.
However, a quick look at both player's game logs seems to back this conclusion. If you look at the frequency of 10-game stretches this year where each player recorded a Volatility score of .65 or below, Ellsbury (58) more than doubles up Granderson (23). In fact, over 60% of Ellsbury's 10-game averages fell into this more elite level of Volatility whereas Granderson only logged 24% of his averages here.
Like I've said all along, this new measurement is just that--new. It's not even beta right now. But that doesn't mean we can't take it out for a spin and see if anything interesting or useful comes from it.