Diego Costa scored 22 goals in 42 games last season to help Chelsea win the Premier League and also reach the FA Cup final.
But he fell out with Antonio Conte during the campaign and was then told via text that he no longer had a future at Stamford Bridge. Costa has since rejoined his former club Atletico Madrid, while Chelsea signed Alvaro Morata to replace Spain international.
Morata has struggled to replace Costa, and former Chelsea interim boss Avram Grant believes that singular act was Conte’s undoing and is the reason the Blues are struggling this season.
“You should not release a striker like Diego Costa so easily and think that everything will be okay,” Grant told Sky Sports.
“Today the top teams do not release anybody. It is a new era because there is a lot of money in the game. It affects you.
“If you take Diego Costa away, you can see part of the reason why Chelsea has not been so successful this year.”
Grant has also advised Conte to stay till next season and prove his worth to the club.
He said: “If I was in his shoes I would be desperate to have one more season to show everybody that I have the quality.”