A new "protection" study using ball/strike data

Here's a baseball study described on a brand new blog by Ken Kovash, who works for "Freakonomics" economist Steve Levitt.

Kovash sets out to check whether "protection" exists. But rather than checking the hitter's batting line for evidence, Kovash checks what the pitcher throws him. He finds two statistically significant effects:

-- pitchers are more likely to throw fastballs when the on-deck hitter is better;
-- pitchers are more likely to throw strikes when the on-deck hitter is better.

I can't completely evaluate the study, because Mr. Kovash's blog just posts an outline of the method. I can't even be sure how to interpret the results, because he gives a coefficient without saying whether it's an increase in the probability, or an increase in the log of the odds ratio.

But I think that either way, the results are barely "baseball significant." Assuming the coefficient is a straight increase in the proportions, then:

-- An increase of .200 in the OPS of the on-deck hitter would increase the chance of a strike by about 3/10s of a percentage point (so if the pitcher would normally throw 60% strikes, he would throw 60.3% strikes instead).

-- Similarly, with the same .200 increase, the pitcher will throw 0.2 percentage points more fastballs – say from 40% to 40.2%, or whatever.

What surprises me is not necessarily that the differences are so small, but that such tiny effects are statistically significant – I guess that's what happens when you have four full years worth of data.

Also, you could argue that the "chance of a strike" number doesn't actually show "protection," since it could be caused by the batter's actions -- swinging at outside pitches he wouldn't normally swing at, or some such.

Hat tip: "Freakonomics" blog.