The disallowed 4th Coventry goal is open to far more debate.
The analysis on MOTD2 was good on this. The handball and kick to the heal, like has been said, are 50/50. There's been instances like those given but also not given. The third one was a mess because the ref signals that the defender played the ball when the replay showed that he didn't. The VAR should have seen this in the replay and called the ref over to the screen. He didn't, but that's not corruption, it's poor officiating.