In order to get this achievement you must 1st unlock the other 950 achievement points, however I just unlocked 49 of 50 achievements which should have unlocked this achievement which it did not.
I would like to thank pronk48mvp whome updated us that NBA2K10 was updated with a patch on 01/20/10 so we could unlocked the previously glitched "Dunk Off" achievement.
Once I got that achievement I went for the remaining 3 I needed and once I got them this one did not unlock so it looks like the patch did not fix this achievement.
If anyone has "legitimentally" unlocked this achievement please post a comment under this post.
For such an amazing game it is unfortunate there are achievement glitches and poor online service.
EDIT: I just did a random game of Team Match Up (5 on 5 with other XBL players) and surprisingly after the game was completed the "ALL NBA" achievement popped up unlocked.
So incase you get all 49 out of 50 and it does not unlock, I recommend doing a random game online for now and make sure you complete the game in it's entirety.