Personally, I'd disagree as we may have Shaw and Darmian, but they are our only senior team full backs. Yes we have young and Valencia, but they are not natural full backs in any way. Yes, CBJ and Varela have both impressed me this season, but they are young and have a significantly high chance of being loaned out this season to further their development because (fingers crossed) Shaw and Darmian will be fit and they won't have game time. Rojo is better of in CB and has been ineffectual (to be kind) at LB this season.
Also, we don't have good depth in CB. We have Smalling, Jones is a walking injury waiting to happen. Blind has done his job well but should be moved back into his CDM role. McNair is not going to last at United even though I like him.
Finally TFM, while a wonderful talent, is someone I would love to see playing in that Carrick role and could be an absolute destroyer in that position.
I would agree we need quality CB to be paired with Chris, but we do need some deeper, more senior squad members that can fill those roles. It has been great watching all the youth this season, in fact the only highlight. But top teams never rely on youth like we have this season.