When David Appelman dropped his newest bomb on us the other day and announced that you could now find customizable heat maps here at FanGraphs, I think it’s safe to say that most of us saber-nerds had our minds blown. Personally, I’ve always admired the work that Dave Allen and other Pitch F/x gurus have done, yet being unskilled in the art of SQL and R, I figured this was a type of analysis that would always be beyond my abilities. Following in the footsteps of other FanGraphs updates, though, this analysis has now been democratized and made available to even the newest of saber newbies. You don’t have to know how to string together code or manipulate huge data sets: all you need is a mouse and a pointer finger.
But heat maps are like any other tool: before you can add them to your toolbox, you have to understand how to use them. Pitch F/x data can be a tricky thing to interpret, and many experienced saberists (myself included) have made mistakes because they didn’t know what they can and can’t do with that data. What exactly are heat maps? What do they show, and how should we use them? Let’s go exploring: