Yesterday, Cole declared to me, "I'M GOING TO PLAY FOOTBALL!". Ok, I said. Go for it. He proceeded to run to the garage to get his helmet ("BECAUSE FOOTBALL PLAYERS WEAR HELMETS, MOM, TO PROTECT THEIR HEADS!") put it on, and run around like a crazy (or drunk) person, falling down on the football randomly.
I think he's got a pretty good scope of the game.
He definitely has the main purpose down: to have fun!