The reason his baseball teams fail in the post season is because he has no high paid, 'elder' leaders on these teams who can manage the stress associated with the post season. His teams are usually too young.
Except that his philosophy and approach tends to ignore these intangibles, thus reinforcing that belief (rightly I think, but not in the levels others think) that some intangibles do matter, to a degree, not as much as, say, drawing a walk, but still...I mean, i'm not a big believer in 'grit factor' (see rowand, aaron) but i think there are some intangibles that come into play.
Not for nothing, but beane also owns (i bleieve) 5% of the A's? It was part of the deal to keep him around since they couldn't afford to pay him what other teams could.
And yeah, he's an egomaniac, moneyball makes that grossly apparent, but then again, if he wasn't would he be as good at what he does (i mean, he gets all the money ball 'credit' when really it should go to alderson)