Edwin Jackson's BABIP isn't low because of balls being hit right at guys or tremendous defense. Instead, it's because 14 of the 18 flyballs he's allowed this year have been of the infield popup variety, and those are the easiest out in baseball.

Obviously, Jackson's not going to induce popups at this rate all season, but it is worth contemplating whether we should really expect all these infield popups to regress into being hits, when they really have no chance of missing fielders in the first place.

You have to look beyond basic per nine ratios to project success or failure going forward. In some cases, a complete regression is appropriate, but there are exceptions. Jackson's infield popup rate suggests that there may be some real improvement that isn't being reflected in his per nine ratios just yet.

So, if we took this exact same early season performance and renamed it "Johan Santana" instead of "Edwin Jackson", would you have the same opinion. If not, why not - it's the exact same performance, after all.

I get that you think Edwin Jackson sucks. That's fine - that's not what I'm talking about here. I'm just wondering why you're willing to make the assumption that infield flies are a subset of outfield flies and are likely to regress into home runs eventually. I haven't seen any research that supports that kind of assumption. The fact that his IF/F rate will drop (and that's not even a question) does not inherently mean that those infield flies will become OF flies, and that's the part of this assumption that I'm challenging.

Just a hunch? C’mon, you can do better than that.

You can’t use statistical analysis and then resort to “just a hunch” when challenged. You sound like the guys who say Jim Rice is a hall of famer now! LOL.

Why not say, “hmm. That information regarding infield pop ups is interesting. I’ve never thought about it that way. But the evdience has shown that over time a player’s BABIP reverts to his xBABIP. And when that happens, Jackson’s going to be looking a lot more mediocre.”

Or you could say, “we need someone to do some research on this infield fly stuff.”

Anyway, good article, and very interesting rebuttal david

Help me out a little bit: I’ve read elsewhere that league average babip is about .290. Wouldnt Tampa’s improved defense do quite a bit to account for .290 – .274 (which is Edwin’s babip as of 5/14)?

Also say you have a pitcher whose “game score” over 8 games is 3, 3, 10, 3, 10, 10, 3, 3 with a lower number being a better game. Is that pitcher better or worse for your team in terms of expected wins than a pitcher who goes 5.6, 5.6, 5.6, 5.6, 5.6, 5.6, 5.6, 5.6? I would think that on a relatively low scoring team, as the Rays have been so far (unfortunately), the first pitcher would be more desirable.

Lastly, is there any research out there on game by game babip vs season averages? What is fundamentally different about a pitcher who hovers around a .300 babip every game vs one who pitches games at a .100 half the time and .500 babip the other half? How consistent is the leauge as a whole?