That there's not a single clear and suitable candidate is a worry for United - it shows the lack of leadership in our team. It's a far cry from times under Fergie when half the team could have done the job and we had great leaders like Robson and Keane.
Rooney and Carrick are the most qualified at United but they have been far from regulars this season and sadly it looks like they are on the way out.
Valencia could be a candidate except he doesn't speak good English and although very strong and determined he seems almost shy when it comes to giving his teammates a bollocking/encouragement respectively (or maybe it's just that he doesn't speak good English)!
I think Herrera is a decent player but too soft for a United captain - I'll never lose that image of Noble carrying him off the pitch last season. I wouldn't like Rojo for a similar type of reason - too much play acting does not make for United captain material.
Smalling could be captain if he were ever to remain fit and consistently at the top of his game for a full season, but it's yet to happen and I question his confidence to be a leader.
Pogba doesn't strike me as captaincy material with his social media, sponsorship deals and image off the pitch. I'm not saying he's not professional whilst at work but it doesn't set the best example to young players coming through.
Young and Fellaini who have recently had the armband probably aren't good enough to be regulars in the starting eleven to be honest so don't make good captains.
The one player it should have been at United this season, and I'm surprised it hasn't been, is Zlatan. He has the ability, confidence, leadership and experience more than anyone. The only downfall is it would be a short term solution before we end up back in the same boat.
This is all why I'm surprised we haven't gone for players like Seamus Coleman or Jordan Henderson (Ireland and England captains) in the past or why we haven't made more of an effort for Kane and Ward-Prowse (probable future England captains). Having those type of leaders in the team is almost as important as having the talent.