If you use Tsearch, you can change the difficulty
1. Download Tsearch
2. Run the game.
3. Open up Tsearch
4. Click Open process, find and click NBA 2k11 in that list.
5. Normally you hit the magnifying glass to search for HEX codes.
Instead in the middle of the screen just add a new cheat (the middle box where it says "description, address, value etc..."
6. when the dialog box comes up, name the description anything.
7. The address for the difficulty (which includes myplayer mode) is 551F694. It is 4bytes and then create a new hotkey for it.
8. The value you want for rookie difficulty is "0". "1" is for Pro. It works like a charm. The good part is, once you do this once, you don't have to do it again once you save your game. YOu can close Tsearch and you're playing in rookie mode. if you need help let me know.
Deltaboy, I gotta thank u for making me realize that this game is completely capable of being manipulated. Not only did I change the difficulty to Hall of Fame, I also turned off all rules that caused me a low grade. I'll give addresses if requested.