One problem with market inefficiencies is that, once they're identified, it's usually a matter of time before they disappear as more players bid up the undervalued asset (or avoid the overvalued one) and close the gap between price and value. Defensive value has recently represented a point of inefficiency in the market for baseball players, but after the Tampa Bay Rays went from worst-to-first by overhauling their defense, the Seattle Mariners jumped on the strategy and added 24 wins to their 2008 total despite their lowest full-season total of runs scored since 1983. There are certainly some teams remaining that don't appreciate the value of defense or don't evaluate it properly, but enough teams are pursuing defense that the inefficiency in the market is either closing or closed.

One remaining area that teams are still trolling for value is the market for players coming off injuries or injury-shortened seasons. The inefficiency here isn't as clear cut as that of defense or the market for OBP before Moneyball -- in which a skill with tangible, measurable value was simply underpaid in the market, but one of risk and risk tolerance.