He said: "Drogba is a key player for Chelsea and we need him. But I didn't think he would leave. He was the Premiership's leading scorer and it would have been a big mistake for the club to let him go.
"There is no one who could replace him who is in the market at the moment. Didi is a great footballer and he understands what his role is at Chelsea.
"He can't complain about the way Mourinho or the club treat him because he is one of the stars of the team and we all have to be treated the same.
"I would have bet anything that Drogba continued with us. He's not going to find a better club in Italy or in Spain and he knows it.
"This pre-season he has looked more involved and committed than ever, both in training and games.
"He has the same motivation and fighting spirit as last season."