I think your viewpoint is a bit arrogant. You are certainly right that more emphasis is put on first month/last month splits and it is often unnecessary. And it is certainly possible that it's just a bizarre coincidence with Teixeria. But we should note that this is true for him year-in and year-out, so I am less likely to think it's just a flukey thing. Also, maybe he knows something about his swing/approach that we don't. Maybe there are significant differences between his two swings. Maybe he doesn't swing a bat until spring training and needs extra time to get both in order. Or maybe it's just BS. We don't know for sure. But I think it's unfair to say with absolute positivity what is true when we don't have all the necessary info.

This is why I think there are issues with lumping guys in based on superficial characteristics. Yes, you found all the switch-hitters, but not all switch-hitters are the same. As noted, some have very similar swings regardless of the side of the plate they are on, while others have wildly different ones. It's the same thing as looking at a players performance vs LHP or RHP. Not all LHP are the same. Rather, we should look for players who actually have more in common and group them accordingly. Knowing that Jeter is 1-4 in his career against Bucholtz is meaningless, because the sample size is too small. Know Jeter is 2000-6000 against RHP is also not that meaningful, because it includes Pedro Martinez, Sydney Ponson, and everyone in between. But if we evaluate pitchers who have a similar arsenal, wind-up/delivery, and otherwise have a comparable pitching profile, we can get a meaningful sample size without so much noise.

Sorry, got off on a rant. Anyway, I certainly recognize the likelihood that this hypothesis is bupkis. But I don't think we can simply dismiss it, and I don't think lumping all switch-hitters in together is necessarily the way to get at the accuracy of it.

I will mess with Excel this afternoon and see what I come up with.

No. If it wasn't the "first month" people wouldn't ascribe any significance to it. If he had a .750 career OPS in June, nobody would try to figure out "why". As for Teixiera, he's just making an excuse to get the moronic mainstream media off his back with their silly questions.