By Karl Matchett.

 

Chelsea are a club in transition once again, much sooner than they expected to be and in a far more volatile way than anybody could have expected, still only eight months after they won the Premier League title under Jose Mourinho.

 

The Portuguese man is gone, Guus Hiddink is in-though another, more permanent, appointment will be made for head coach in the summer. The new new boss will have a mix of established talent and young prospects to work with, as well as an array of veterans who continue to divide opinion over their lingering suitability and level of quality.

 

Whoever comes in it can be expected that the blues will make significant changes to their squad in the summer, and still potentially even an addition in the final days of this transfer window; here we identify the three most critical areas that the Stamford Bridge club must invest in, regardless of manager or which transfer window they make their move in.

 

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Central midfield

 

Beginning at the core of the team, Chelsea's strength under Mourinho and previously had always been in their blend of tactical or positional dominance in midfield, combined with enormous physicality and a goal threat from deep. Of course they still have that on paper, with Cesc Fabregas and Nemanja Matic a title-winning combination, but the depth is perhaps no longer there and those two have also suffered huge down-turns in form this term.

 

Whether Cesc continues to be deployed as a more advanced option is yet to be seen, while Matic has been linked with a summer move away and Ramires has already departed.

 

It is likely that Chelsea need to add multiple bodies in this area of the pitch, but a first-choice starter to protect the back line and start spells of possession from deep is an absolute must, whether Matic remains or not. Much of which characteristics the potential second central midfield signing carries will depend on how the new boss wants to use Cesc, a tremendous talent on the ball and a scoring option when used further forward.

 

Full-back

 

While Chelsea's established pairing on either side of the defence of Cesar Azpilicueta and Branislav Ivanovic have been reliable and productive for several years, this year has seen both put in sub-standard performances and deliver less final-third output than is ideal. That goes double for Ivanovic, especially after his inept defensive work in the opening months of the campaign; there remain plenty of Chelsea fans sceptical of the wisdom of giving him another year contract as the club have recently done.

 

The club spent big on attack-minded left-back Abdul Rahman Baba last summer but he hasn't yet made much impact. Out on loan, Chelsea have Nathan Ake impressing at left-back for Watford, with the likes of Wallace and Tomas Kalas also away on temporary spells, but few youngsters have managed to break into the first-team scene after loan deals in recent years.

 

At least one new face is required for the back line to return to its former formidable level in both halves of the pitch. 

 

Striker

 

The final area, and an absolute must-have, is a re-ordered striker list for the club. This season Chelsea have been operating with an injured or out of form Diego Costa, a colossal waste of resources in on-loan Radamel Falcao or Loic Remy, who clearly doesn't want to be at the club. 

 

While the likes of Kenedy, Nathan, Dom Solanke or Patrick Bamford may go on to play more game time in future seasons than they have with the seniors so far, a first-choice and secondary option are vital for Chelsea to sort. In theory, Costa and Remy is an ideal one-two, but it hasn't worked out that way.

 

Chelsea have never been afraid to spend big on their main goalscorer-think Andriy Shevchenko, Hernan Crespo, Didier Drogba, Fernando Torres, now Costa-but the key to their reasonably sustained success is that they have replaced those in attack who did not offer the end product that the rest of the team's set-up required.

 

At the very least, a high-quality back-up for Costa is needed this summer due to his physical problems as much as his consistency; just 32 goals scored in the Premier League this season only highlights the importance of this position being upgraded, especially given the porous nature of their own defence and the varied and effective front lines of their rivals.

 

Chelsea will no doubt be a force again next season and certainly have the financial muscle to make the changes in a single window, but it needs careful planning and an eye for an almost guaranteed success with one or two prime targets if the new signings are to catapult the blues back up into next season's title talk.