That has now spread, with some modification, from EA's three major pro simulations—FIFA, Madden and NHL, to somewhat similar concepts in MLB 12 The Show and now, NBA 2K13. The basic goal is the same: Acquire the best players available in a virtual market, using currency that can be earned through completing and winning games. It's noteworthy that NBA 2K13 will have retired all-time greats available—Karl Malone is shown in this video.
While the structure is, broadly, very familiar, everyone throws their tweaks into it, and MyTeam's big differentiator is that a player's acquisition value will vary day-to-day depending on how he's performing in real life. This gives team managers a buy-low/sell-high incentive to building their squads, provided they're following the league closely. It also makes it hilarious when someone ends up a total bust. No word on whether currency will be sold for real money, though.
For more on the mode, see this five-minute video, with producer Erick Boenisch.