Every year or so, the same question is asked: how is the Moneyball strategy working out for the Oakland A's. This year's answer is: pretty damn good.
Additions like [Frank] Thomas, motivated by this incremental approach, help explain why the A's have won so many games in recent years even though they've consistently traded away or declined to re-sign their top players (Jason Giambi, Miguel Tejada, Tim Hudson, etc.), who demand top dollar--and largely on the basis of past performance. In short, Beane has bought low and sold high repeatedly and systematically, and as a result the A's have won more games this decade than every team in the league except the Yankees (whose team payroll is routinely two-to-four times larger than Oakland's).
Check out the current positions of the A's and Yankees on the salary vs. performance graph.