Sports games actually often go through quite dramatic changes to their mechanics. Much more so than first person shooters or things like that. I don't know football games so well but baseball and basketball ones, golf, boxing, hockey, whatever, they are always totally changing everything. I guess because they are more concerned with trying to convey the experience of these physical actions than they are about follwing the tradition of other games. I mean like nobody wants to learn to aim a gun in a new way, they are more interested in a new context/new rules for where they shoot them, but something like taking a free throw is pretty up for grabs. And certainly they'll go over massive overhauls the next round of consoles when (I can only assume) everyone will incorporate some form of wii like motion controls.