THE BOOK--Playing The Percentages In Baseball

I wrote this in the comments section:

In the article, when you say the slider moves toward RHB, is that a typo?  As you say in your comments, a slider always moves away from a same side batter, by definition.

When I watch a game on TV I rarely do not know what a pitcher is throwing.  I am always surprised at the number of mystery pitches on the gameday data.  I wonder if it is more of a data problem than anything else. Can you look at video that corresponds to mystery pitchers?

Anyway, as I have said many time with regard to analyses of pitch selection, without knowing the norms for MLB pitchers on the whole and especially similar-type pitchers, these percentage analyses mean almost nothing.  Of course Joe points that out and I am glad that he did.

There are only a few principal reasons to pitch differently in different leverage situations and I am not sure that looking at leverage is the best way to do it anyway.

You want to look at the win (not run) values of the walk, ball in play, batted ball out, and K.  When the value of the K is a lot different than the batted ball out such as with a runner on third less than 2 out and a close game, obviously the pitcher wants to throw whatever gets him the most K’s without worrying about a walk (unless perhaps the bases are loaded or to some extent with 0 out).

When leverage is low generally the pitcher wants to throw whatever are his best control pitches to minimize walks without worrying about hits.  Also, I suppose he wants to limit his pitch count as much as possible even if it means letting up more runs.

Even in similar high leverage situations, the run values of the various outcomes can be quite different.  Often a home run is what you want to avoid, such as a one run game in the 9th with no men on and sometimes it is just any hit, such as a runner on 2nd or 3rd with 2 outs in a tie or one run game.

When you want to avoid a home run, you pitch differently then just wanting to avoid a hit.  And trying to avoid a hit or walk, such as with the bases loaded in a tie or one run game requires even a different pitching approach.

And of course, tracking location in addition to pitch type in different situations is important.