No top manager loses 8 - 2 to their rival. It just doesn't happen. How the fuck are the players going to recover from such an embarrassing affair?

Let this ride out until he totally embarrasses himself and decides to walk. We can't sack him now because we don't have anyone that can come in and repair the damage right away. But while there are still people out their supporting this clown and believing the board are the main culprits, let him stay on until all the doubters are convinced that this guy is past it.