Chris Smalling (Manchester United)
Long a figure of derision, Chris Smalling gets unfair criticism a lot of the time. He's been a mainstay of Manchester United's back line for 6 years now, something that doesn't happen if you have no talent. Comparing him to their other options in the centre-back positions, though, shows why he's the weakest defender.
Eric Bailly has been an excellent find, a powerful and confident defender whose struggled with injuries since arriving. Victor Lindelof was signed for a lot of money in the summer transfer window and looked clumsy, to begin with, but will surely find his feet soon. Marcos Rojo and Daley Blind offer the balance of being left-footed, while Phil Jones, despite his somewhat comical reputation in the media, has the commitment and fearlessness that Smalling lacks.
The impression one gets when watching him play is that a skilful defender in the mould of Rio Ferdinand but without the confidence to back it up. It always feels like a big mistake is lurking in Smalling's performance. That he's been the senior leader of the defence for much of the past few seasons speaks volumes of Manchester United's poor recruitment; why Jonny Evans was allowed to leave remains a mystery.