#3 Fans
Chelsea have some of the most impatient fans in the world. But, at the same time if they like you they won't stop prasing you or signing your name either. There is not just one example of it but several.
At one time Chelsea fans used to sing chants for Alvaro Morata but as soon as his form detoriated he was booed. Jose Mourinho is the most successful manager in Chelsea's history but the Stamford Bridge faithfull did not spare even the Portuguese.
The Chelsea hierarchy will allow Sarri to leave because of his poor relationship with the fanbase. But this is not a strong reason to allow him to leave. Yes, the relationship has been poor but the Europa League win has somewhat reedmed realtionship with many fans.
There have been times when Chelsea fans have shouted 'We want Sarri out'. There were also times when Chelsea were winning and these same fans were shouting 'ole, ole, ole' in praise of Maurizio Sarri.
It is a simple thing for any fan to sing for the players and the manager while winning and jeer them while losing. If Sarri is there for next season and starts to win games then fans will once again sing his name and the relationship will be good as ever.