Pepe Reina has questioned Chelsea's decision to replace Rafael Benitez with Jose Mourinho.
Benitez, who is now at Napoli, was allowed to walk away from Stamford Bridge over the summer - despite the Spaniard helping the Blues win the Europa League and a spot in this season's Champions League.
The former Liverpool manager was replaced by Mourinho but Reina believes Chelsea owner Roman Abramovich has made a big mistake in letting the Spanish tactician leave the west London side.
Napoli loanee Reina, speaking to the Daily Mail, said on Benitez's spell at Chelsea: "They never gave him the opportunity to work in peace and still they reached the semi-final of the FA Cup and won the Europa League.
"He finished third and made it into the Champions League, which was by then probably the biggest target, and he did it with all the people against him.
"It proves once again how good he is that even in those conditions he can work very, very well. They’ve got their reasons, good or bad. I can’t read their minds, but it’s definitely their miss."
Benitez's Napoli have started the current campaign off in fine form by winning five games from a possible six in Serie A thus far.
Reina and Benitez return to England this week as Napoli take on Arsenal at the Emirates Stadium in the Champions League on Tuesday.
The Italian side are currently joint top of Group F alongside Arsene Wenger's Arsenal side.