I dont agree that people are tired of the yearly sports releases because it has been mentioned that Nba2k10 sales have increased.
Look this is the bottom line. No matter the economy, you make a quality product with a good release it will sell. Two games are a testiment to that point, Ufc Undisputed and Batman:AA. Two new IPs that broke sales estimates.
Since I brought up the UFC let me make another point about the economy. UFC has done extremely well in the PPV market even with a PPV every month. Guess what company blamed the economy for their lackluster PPV sales, the WWE. It's so easy to blame everything else other than the obvious, your product.