Frank Lampard's name was a particularly notable one on the Premier League's list of players released by clubs.
Though he may yet sign a one-year contract to extend his fantastic Blues career, something that may not be clear until after the World Cup, the possibility Frank Lampard has played his last game for Chelsea is looking more and more likely.
If he does depart, he will leave a very large hole in the goalscoring department of Chelsea's central midfield, and it will be something Mourinho will likely address as part of his summer transfer plans.
But it may turn out that the Blues' willingness to let an ageing Lamps go frees up an opportunity for one of Europe's talented young midfielders to come into the club.
One of the players they have been linked with is Hamburg's young attacking midfielder Hakan Calhanoglu, who has been outstanding for Die Rothosen despite the club's troubled season, which included narrowly avoiding relegation in a playoff tie.
The 20-year-old is perhaps most famed for scoring a ridiculous free kick against Borussia Dortmund a few months ago, but that was just one of 11 goals he netted over the course of the Bundesliga season.
Calhanoglu was eligible for the German national team but ended up turning out for Turkey after starring for their youth teams. He joined Hamburg from Karlsruher in 2012, but spent the 2012-13 season on loan at his old club where he initially demonstrated his goalscoring form with just over a goal every two games.
The youngster is in demand across Europe, with Arsenal also rumoured to be interested, while Bayer Leverkusen were reported to be favoured by the player himself.
Wherever he goes, the opportunity to play in European competition is of paramount importance to Calhanoglu, who is quoted as telling German media: "I told them [Hamburg] that I want to go - no matter whether we play in the first or second division.
"I would definitely leave Hamburg. The fact is, I want to play in Europe and I want to make my parents happy.
"I want to go as far as Ronaldo and Messi. I want to be a world star."
Chelsea may have to move quickly if they do decide Calhanoglu is the man they want to fill Lampard's boots.