It is, of course, Arsenal fans who will feel most aggrieved. Arsene Wenger’s decision not to take up the club’s first option on Fabregas when it became clear his future lay away from Camp Nou, knowing what would likely happen if he failed to act, could prove as defining as any in his rollercoaster reign.
The Fabregas deal may also cause considerable consternation in Manchester. Manuel Pellegrini has long admired the Spaniard, while Louis van Gaal may now be pushed closer to the injured and less proven Kevin Strootman as he searches for the midfield successor to Paul Scholes that Old Trafford is crying out for.
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But their pain is Chelsea’s joy. The primal thrill that accompanies a marquee signing can only be heightened by getting one over your big rivals so publicly.
Then there is also the fact that Fabregas, despite being made the scapegoat for many of the failings of Tata Martino’s ill-fated campaign at Barcelona, remains a player blessed with spectacular talent and, at 27, one who has every reason to expect many more good years at elite level.
No player got more assists from open play (13) or created more clear-cut chances (27) in Europe’s top five leagues last season. For a team whose title challenge was derailed by a chronic lack of imagination against the likes of West Brom, Aston Villa, Crystal Palace and West Ham last term, his arrival could well provide the missing piece of the jigsaw before Diego Costa is even mentioned.
With Fabregas and Costa secured and Mourinho at the helm, Chelsea immediately assumes the position of favorite to win the Premier League. And with Nemanja Matic and Mohamed Salah eligible from the start, a team that scrapped its way to the last four of the Champions League last season should be able to at least match that achievement with greater style next season.
There is no small irony in the fact that Fabregas has been the man chosen to fill the creative void so obviously left by the departure of Juan Mata in January, a player deemed by Mourinho tactically undisciplined to the point of idle luxury.
Fabregas, remember, is a player once praised by Pep Guardiola for bringing “anarchy” to his fiendishly organized pressing Barcelona side. The Bayern Munich boss, a notoriously neurotic operator, soon grew weary of trying to find a place for Fabregas within his system and left him on the bench. It will be interesting to see if Mourinho, every bit as tactically demanding of his players, can succeed where his managerial nemesis failed.
Logic suggests Fabregas will find his regular home alongside Matic at the base of a Chelsea midfield that now appears to tick all the boxes. Mourinho may rely entirely on the giant Serb to shield his back four or partner him with the bustling Ramires to give his new signing more freedom to roam forward.
Such a role might bring him into conflict with Oscar, but the Brazilian’s limp and jaded performances in 2014 suggest another playmaker is needed to lighten the load.
These are questions Mourinho must ponder, but they are the kind any manager would relish. He now has a player who may necessitate a tweak of style but also one of genuine world-class ability who, by his own admission, has “unfinished business” in the Premier League. Chelsea will hope he wastes no time in settling it.