It's sad because when he plays, he's quality and I agree he's useless if he's not playing- depending on his pay, I'd keep him for 50% ish of games at 70 mins whilst blooding players like Jack Robinson (kind of like Spurs do with King).
It's a shame! Kelly, Agger, Carra and Fabio would be a great back 4 and at the moment, none are available!
Perhaps that shows our strength in depth, something we're often criticised for, in that our defence got battered yesterday with injuries and still worked well as a unit.