Check out the new NBA 2K11 article from Jon Robinson, titled Is it the Shoes?
"... as gamers play through "NBA 2K11" they will constantly be rewarded with new pairs of cyber shoes. There are 40 shoes total in the game including 25 pairs of Air Jordans along with the CP3s, Melo 5s, and other shoes from the Jordan line to fill out the closet. But it's not about scoring 80 points in a game or grabbing 22 rebounds in order to unlock certain pairs. It's all about time invested.
"The way they unlock is every couple of hours you get a new pair," explains Boenisch. "The shoes also have attributes on them, so this becomes really beneficial both in My Player and MJ Creating a Legend mode. And shoes can be unlocked anywhere in the game, whether you're playing online or franchise or practice mode. Your timer is always running and shoes are always unlocking.
"And the order you get them in is random. It's strategically random where the rarest shoes in real life are the hardest to get and are unlocked toward the end while the common ones are unlocked upfront. But if you and I are playing next to each other at the same time, we're going to unlock shoes in a different order. So you can show your friend that you got the Jordan 12s, but maybe he got the 1s and 23s."