The fact that he picked the same squad, except, did he not use Rashford(I've already forgotten). The performance was shocking, largely because he was being a giant girl and refusing to drop Rooney and don't forget his post game comments. Rooney picks where he wants to play, he stated openly that he doesn't have the experience to tell Rooney what he thinks is best for the team. He's already admitted he has zero control over Rooney and effectively with that statement told the team that if they are a big enough player they have power over the manager and not the other way around.
He should have been fired for that single performance that was dominated by a shocking Rooney followed by him stating that in effect, Rooney gets to control how the team plays not the manager.
Throw in being bent as hell and he should never have gotten near the managers job. Fat Sam is one of those with persistent rumours about dodgy deals going on, quite aside from the dire football his teams have produced throughout the years. Nothing in his entire career indicated a completely honest manager nor a good manager, how he got the job I don't know and since he's got it he's embarrassed himself with both team and outside the team issues.
Outside of bungs he supposedly took(which can't always be proven, as a bung can be an increase in a normal payment so it doesn't look shady), there were also many rumours about how he filled his teams with players his agent was also the agent for. This would allow him to effect transfers and wage negotiations from both sides. Lets say player A would only be offered 20k a week at other clubs, but Sam tells the agent they can afford 30k a week so tells the agent to demand 40k a week. The owners don't want to pay that but Sam then tells them how important and good he'll be so gets them up to 30k a week. So Sam has gotten the player 50% higher wages, the agent gets 50% more from his take home so maybe the agent offers Sam 5% off his agent fees for him, in effect giving him extra cash for screwing over his own clubs.
Again I'll say, nothing I ever saw from him suggested England manager and his response post game to a truly woeful performance just made it clear he's not a good manager.