Billy Beane gets credit for hiring a statistician when no one else had one. The A's don't ever have good offenses, but they rebuilt in '02 by using guys like Hatteburg and not being completely horrible (which is what moneyball is about). It was a study of how stats can help find market deficiencies to help a team gain an advantage (deficiencies which no longer exist).
Market inefficiencies, I think you mean.
To further Bjin's point, the "Moneyball" philosophy isn't about any one style of baseball. It's about understanding how much each aspect of play contributes to a team's chance to win, and then identifying those aspects that are undervalued (and therefore less expensive) and concentrating your limited budget there to get the most wins for your buck.
Pitching is relatively well understood and valued, so the only way to obtain a market edge on pitching on a limited budget is to develop your own and then trade them when they start to earn bigger contracts. (Reclamation projects can also be cost-effective but are higher risk.)
So the opportunities to gain a "Moneyball" edge were seen to be among position players - in particular offence, more particularly OBP.
Here's the problem for Beane and company: over the past decade, and due in large part to the success Beane and his disciples have achieved, most teams have caught on to the significance OBP to the point where it's no longer undervalued in the market. So he has to find another area that contributes to wins, and which is undervalued compared to its contribution.
The argument's been made that defence is the next inefficiency, and there's something to be said for it.
Speed still appears to be fairly valued compared to its impact on wins, but that's an improvement on being overvalued, so over the coming years that will probably see speed become more of a focus for cost-conscious teams.
