Alonso has been announced as the new permanent Chelsea manager on a four-year deal as he hopes to begin work this summer ahead of what will be another tough campaign for the Blues.
Chelsea have had a dreadful campaign, finishing 10th, which means the club will not participate in any European competitions next season.
There is a lot of work to do for Alonso before the season begins, namely reshaping a Chelsea squad who look useless in defence and toothless in attack.
Speaking to Standard Sport, via MrRaffle.com, Desailly believes that Alonso must instil his philosophy, which means a clear out of several players.
“The problem he is facing is coming into a club that is completely full of players. When you look at Chelsea today, they must have something like 75 players around the world who still have a contract with the club.
“How do you allow a coach to define and organise his philosophy around the specific players he wants to put into the system?
“He really has to sit down with himself and erase the players who do not match his philosophy. But it is super difficult with Chelsea because they have so many players already. How do you get rid of them to build your system?”
Alonso does not officially begin his tenure as Chelsea manager until July 1st but will be working on who he wants behind the scenes and that players he will aim to sign especially as the World Cup approaches.
Chelsea first travel to Australia for friendlies against Western Sydney Wanderers and Tottenham Hotspur before the season starts, as he gets a good look at his side.