How do you update NBA 2k13 roster?

Once u here the roster change in real mlb, wait about 2 weeks then (with with live on) start the game, then when is says download in progress , that means it is updating the roster. But u have to be logged into your live account before you start the game or it won't work, like I said when it counts in percent to 100 and says download in progress, its updating what is new in MLB like trades and call ups