In the last 5 years he has won: 1 PL, 1 second place with a team that should be battling for relegation as it seems, 1 Europa League and a couple of mickey mouse English cups.
What did you expect him to do? Win the Champions League with Man Utd? It was a miracle that he managed to get past the group in the first place.
His only fault was not realizing that both at Chelsea and Man Utd in this decade the culture is completely alien to what he needs to have around him. He's a manager of men, not of spoiled brats.
Same applies with Conte who was either going to get fired or tame the brats of Chelsea back in September/October. Then they protested because it was "too much" and they fell into oblivion once again.
Same also applies with Simeone who will not tolerate that kind of attitude.
It's no surprise that in recent years the type of managers that succeed in the PL are the so called players' managers. Guardiola and Klopp are this type of coach, in their own separate ways. The days of respect for guys like Ferguson, Mourinho and Wenger is way past it. Even Ferguson grew more tolerant in his final days but when he retired Man Utd became a complete recreational center for overpaid athletes.