Phil Birnbaum at Sabermetric Research picks apart the Wharton School research I doubted yesterday and comes to a way smarter and better explanation: “The factoid, ‘players hitting .299 or .300 batting a whopping .463 in their final at-bat’ is true — but it’s the result of cherry-picking the AB in the sample. If the player got a hit to pass .300, it was likely to *become* his last at-bat, as he tended to sit out the rest of the season. But if he made an out, the AB wouldn’t be his last.”
Tedquarters
Ted Berg
Tedquarters 
phil birnbaum rules, doesnt he?
A) Phil Birnbaum is better than the rest of us.
B) This is unfortunate, because the original paper those guys wrote was about how round numbers affect our behavior, and *they’re still right.* Players are changing their behavior, sitting out games or at-bats they otherwise might not have so they can finish the season with a .300 BA. The authors actually have evidence to support their primary argument! But then they went and made the extra claim that guys suddenly become better baseball players, and now they look like fools. Oh, hubris.
C) By the way, doesn’t this further drive home how totally awesome Ted Williams was when he batted .406?