Because he is the superstar. If he is going to want to take the credit for when they win, then he will be responsible for the L's pilled up. Same theory goes for every superstar, and the QB's in the NFL. If you get paid the most, and are the best player on the team, you will be responsible for the W-L records. Fair or not, its the way it is.
Can we call him anything but DC as we already have a DC in Darren Collison.