Jose Mourinho likes his players to fit a certain style of play, and in order to do that, they need to be the right fit for his tactical setup.
Just looking at some of his signings at Real Madrid gives you an idea as to how Mourinho likes to operate as a manager. Fabio Coentrao, Michael Essien, Sami Khedira, Luka Modric and Mesut Ozil all joined the Portuguese genius at the Bernabeu and all fit the typical workhorse, energetic style of player he likes.
And after being officially announced as Chelsea's new manager for the second time, there's no doubt that the 50-year-old needs to address the changes at Stamford Bridge.
Florent Malouda, Yossi Benayoun, Ross Turnbull, Paulo Ferreira and Hilario have all left the club following the expiration of their contracts, but it seems the quintet will not be the only departures from Stamford Bridge this summer.
Here's our thoughts on who may be leaving Chelsea as per the wishes of the "Special One." Be sure to let us know your thoughts and opinions below, as always.
In Gary Cahill's defence, not many defenders score more goals than him, and in that sense, he is an asset to the team.
But under Jose Mourinho, he may find it rather different. Even despite making 45 appearances for Chelsea last season, he rather likes his defenders to stick to their own job of protecting their goal. And that could lead to Cahill seeing his chances limited at Stamford Bridge.
Perhaps the two biggest issues that continue to undermine his ability as a defender are his lack of composure and consistency. When he is on the ball, you gain a sense that he doesn't want to be. He usually struggles to find a short pass to a teammate and instead launches the ball forward.
Mourinho likes to play with the ball on the floor and his players to have confidence on the ball. Cahill's defensive partner David Luiz possesses the sort of level of technical ability that should see him retain his place in the side.
If Cahill is forced to leave the club, there would be no shortage of admirers in a player who is only 27 and is a full England international.
Jose Mourinho likes his strikers physically adept, quick and hard-working, and it's nothing new; we witnessed that with Gonzalo Higuain and Karim Benzema at Real Madrid.
But former Newcastle striker Demba Ba, who signed for £7 million in January to help solve the Blues' striking crisis, has failed to hit top form while at Stamford Bridge, scoring just six times in 22 appearances for Chelsea.
The 28-year-old has been limited to domestic games due to his Europa League ineligibility and has struggled to forge an understanding with Chelsea's attacking trio of Juan Mata, Eden Hazard and Oscar.
The Senegal forward's quality is undeniable, with his stunning strike against Manchester United a clear indication of that. But that isolated incident will not be enough to convince Mourinho that his future is in West London.
But with the in-form striker in the shape of Romelu Lukaku pushing for a first-team start, it seems the Belgian would be the preferred choice, with the 20-year-old possessing great pace and terrific strength as a lethal combination.
That's right, you've seen the name. But you can relax, Chelsea fans, because while Oriol Romeu could leave this summer, he isn't going anywhere permanently.
After suffering from a cruciate knee ligament injury back in December, Romeu was fit enough to be included in Chelsea's Europa League final squad after six months out.
The Spaniard had shown signs of improvement before getting injured and made nine appearances after the departure of midfield trio Raul Meireles, Yossi Benayoun (loan) and Michael Essien (loan) gave him more opportunities to play.
Operating as a centre-half or defensive midfielder, Romeu is the type of player that Mourinho will welcome having in his squad. The only underlying problem is his fitness, and a wise head like the Portuguese boss would know that Romeu must be nurtured back into the fold.
A loan move to Celta Vigo, where Romeu's former Barcelona B coach Luis Enrique is situated, has been touted, via the Spanish media outlet Mundo Deportivo. And it could well be a move that suits all three parties while the 22-year-old gets back to full fitness.
He was tipped for a bright future at Chelsea after making his first-team debut four years ago, but after two years on loan at Hamburg, Jeffrey Bruma could see his days at Chelsea coming to an end.
Bruma is fully aware of the defensive options that Chelsea have at present, and with fellow defenders Tomas Kalas and Kenneth Omeruo also returning from loan stints, the young centre-back knows that he may not get the opportunity at Stamford Bridge.
It would be a shame if he did leave after impressing on several occasions with Hamburg, and despite their decision to turn down a permanent switch, that should not be a reflection on his time in Germany.
Nevertheless, with numerous options for the West London outfit to choose from, it's unlikely that Mourinho will fight to keep him from leaving.
When you think of Chelsea's attacking midfielders, the popular trio of Juan Mata, Eden Hazard and Oscar, also known as "Mazacar," are the names that spring to mind.
Some forget that the likes of Kevin De Bruyne and Lucas Piazon are out on loan, while the arrival of Andre Schurrle would certainly bolster the squad's quality in that position. It's a shame then that German winger Marko Marin is now the forgotten man at Stamford Bridge.
A player who promised so much will be disappointed to have delivered so little, and Chelsea may be regretting investing the £7 million in a winger who has a history of injury problems.
What he used to possess was an extra burst of pace that could take him past his opponents, but he looks forlorn and lacking in self-belief, to the extent that he no longer tries his direct approach. In addition, he lacks physical strength, something Mourinho is a fan of, and therefore is susceptible to losing possession.
Marin looks very short of confidence, and the fact that he made just 15 appearances last season suggests his time at Stamford Bridge could be short-lived. Goal.com reports that the 23-year-old has said he will wait until Mourinho makes his decision on his future before making any necessary plans.
It appears increasingly likely that his plans may include finding another club this summer.