That .438 number is interesting and even more interesting when I see the James chart you supplied, Scotti. Your comment about de-shifting shifts is also well taken.
If we use that .438 to informally compare with league average in all cases (about .260), it looks pretty attractive! But this may be one of those places where BA is a little misleading. 1) The hitter chooses to bunt for a hit when the time is right (Shifts, pitcher, pitch), so that is by definition a non-random sample. 2) That big ol' BA is probably stealing some production from BB. 3) as one comment on the James site noted: the data doesn't include at bats where abandoned bunt attempts messed with a count and the at bat was concluded more conventionally. And 4) bunting for a hit takes ALL the production away from Slugging (the definition of small ball).
Still I will look at things a bit differently the next time I see a position player laying one down to the third base side of the infield.