Chelsea loss highlights defensive problems

After a poor defensive performance during the 3-0 loss at Manchester City, is it time for Jose Mourinho to invest in a younger back four?

"I've never seen them this disjointed" stated Gary Neville, who was watching a Chelsea side struggle to cope with Manchester City's ferocious attacking threat throughout a gripping clash at the Etihad Stadium.
City's danger was evident from the offset, with Sergio Aguero almost opening the scoring within the first two minutes after David Silva had expertly sliced through a flimsy Chelsea defence, only for the Argentine to be thwarted by an onrushing Asmir Begovic - which would become a recurring theme in the first 30 minutes.
The former Stoke stopper pulled off two more excellent saves with just 17 minutes on the clock, as City ran rampant over an unrecognisably petrified Chelsea side. Their famous defensive shape completely deserted them, with Aguero firing off four shots in the opening half-an-hour - an interesting statistic considering that no player had more than five on goal in a game this season.
Last week's draw with Swansea showed Branislav Ivanovic and Cesar Azpilicueta's inability to attack their opposing full-backs, while the central defensive partnership of John Terry and Gary Cahill was highly prone to leaving space behind for attackers to exploit. Manuel Pellegrini's men drew up their masterplan, and they executed it with brilliant ease.
Terry's half time substitution  - the first time he has ever been replaced under Jose Mourinho - represented the Portuguese boss' willingness to withdraw anyone from the pitch in order to seek a result - but even the arrival of the pacier Kurt Zouma did nothing to prevent further City dominance, who targeted the usually rock-solid Ivanovic.
The Serbian has been an ever-present in recent years, but he could be next on Mourinho's hit-list following his worryingly poor start to the season. After taking a caning from Swansea's Jefferson Montero last Saturday, Ivanovic was often found sprinting after City's Raheem Sterling - who surged past the 31-year-old with baffling ease on several occasions.
Not only did he fail to contain the electrifying Sterling, but his inability to do the simple things will cause the greatest concern. Vincent Kompany muscled off Ivanovic to double City's lead, while the Serb was at fault for the third goal - needlessly giving the ball away just yards outside of his own area.
It seems bizarre and a bit alien to question Chelsea's usually-robust defence, but does the defeat warrant an overhaul in the Chelsea back four? The withdrawal of Terry, Cahill's shoddy first-half performance and Ivanovic's struggles suggest that it may be time to invest in a younger, fresher defence before it's too late.
Less than half an hour after the game, the Blues confirmed the deal of left-back Baba Rahman from Augsburg, which could see Azpilicueta move into right-back - a position in which he has spent the majority of his career in - while the summer-long pursuit of John Stones continues to drag on.
Everton's chiefs will undoubtedly be delighted onlookers, with Chelsea now likely to return for Stones with a bid that might reek of desperation - giving the Toffees more leverage on the negotiation table.
A critical two weeks awaits, with the transfer window nearing a close. Will Mourinho stick with his reliable troops? Or will he deploy a new system come September? Only time will tell.