Thank You, Brewers Fans

With help from Eric Seidman, I decided to also check whether this was true of all left-handers versus all right-handers, to see if this was simply a fact of handedness, rather than an implication of the shift, and I found that it was the shift…..This BABIP spike is not common to all left-handed hitters, but only to those powerful pull hitters against whom defenses regularly employ the shift.

the tables in the … were not contrasting lefties that have been shifted against lefties that aren’t shifted. Nor did I see anything that addressed cause and effect as you implied, but merely correlation. You (indirectly) indicate that the BABIP rise for lefties with runners on is because the shift can no longer be employed on them, which results in a drop in their BABIP with no one on. This seems a logical conclusion to draw, but there could remain the possibility that lefties have a better ability to be clutch, due to some aspect of their right brain dominance or some magical force in the air (ie something else I haven’t thought of). I guess to discount the right brain dominance possibility you’d have to separately analyze bats left, throws left from bats left, throws right. Also, are there any circumstances with runners on where you can still employ the shift? I would guess you could do it with a runner on second, but no where else. So, are you looking at things considering all baserunners as canceling the shift?

As it’s an infield shift, I would assume that outfield positioning does not alter (at least significantly). So I would expect, given your hypothesis, that two further things would be true.

a) ISO would be very similar in shift vs non-shifted situations, and might actually be lower in situations where the shift is employed than when there is no shift (you’re taking away some liner doubles, and encouraging opposite field grounder singles).
b) BABIP on fly balls should be the same in shifted vs non-shifted. Granted, this counts on the stringer distinguishing between a flyball and an infield-catchable liner (assuming defensive positioning was directly under said ball). BABIP on liners should be depressed for shifted-on batters. BABIP on grounders should be slightly depressed for shifted on batters and should be the cause of the mass-effect upon the overall BABIP (even though liners will be more significantly impacted, as the numbers of liners are low, the effect from said liners will also be low).