Thursday, August 13, 2015

R.A. Dickey's fastball is just fine, thank you very much

FiveThirtyEight posted a thought-provoking article this afternoon applying game theory to FanGraphs' "Pitch Values" data. For the most part, game theory is a very useful way to interpret the Pitch Values data. If a pitcher is getting great results with his curveball and terrible results with his change, he should throw more curveballs, even if that means opposing batters will start to expect more curveballs and do a little better against them.

The 538 article does a specific analysis of R.A. Dickey's numbers, and that's where they go wrong. They assert that Dickey should be throwing a lot more knuckleballs, because his low-80s fastball, admittedly, is pretty darn pathetic. Given that Dickey is already throwing his knuckler for 87% of his pitches, it stands to reason he should reserve the fastball for throwing batting practice only.

What the article fails to grasp, though, is the role of Dickey's fastball in his arsenal. Dickey primarily uses it when he's behind in the count when he really needs a strike. It's not something he uses much on the first pitch. I'm not sure if FanGraphs' pitch values adjusts for this sort of usage; given that Dickey's throwing the fastball on a lot of 3-0, 3-1 counts, it shouldn't be a surprise that he walks a lot of batters with it and rarely gets strikeouts from it.

More importantly, though, the fastball is there to set up the knuckleball. Batters will try to rush their swings to take a cut at the fastball, only to have their timing messed up when the knuckler comes on the next pitch. In this way, Dickey uses the fastball as a waste pitch the same way other pitchers use brushbacks or fastballs at eye level to set up their breaking stuff as strikeout pitches.

So, R.A., don't pay too much attention to the latest from FiveThirtyEight. They've oversimplified the issue. It's perhaps a case of a little knowledge being a dangerous thing, and a classic error of economics that they've made some problematic assumptions in coming to the conclusion they did.

One of the key points of game theory for this sort of situation is that altering your strategy (i.e., altering the percentages of the time you choose different options) will alter your own results as well as influencing the strategy of your opponent. Dickey can't simply throw more knuckleballs without giving up the happy side effects created by the use of his fastball.

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