Ranking our defenders:
1. Bailly (24) - Has been injured too much this season but he has shown as recently as the Liverpool game that he is our best centre back and has the highest ceiling in terms of potential and the level that he can reach.
2. Smalling (28) - Reliable defender, biggest goalscoring threat out of all of our centre backs. On the ball he is average, but he is nowhere near bad, hes good enough imo. Long-term however I think he should be our backup centre back to Bailly and whoever partners him.
3. Rojo (28) - I've had him at 2nd all year but Smalling's recent goalscoring has elevated him above Rojo to 2nd. Crap left back, but at centre back he was a part of the best partnership I've seen us have since Vidic and Rio is Rojo and Bailly, unfortunately as a result of that serious injury this season has been a write-off for Rojo. Hopefully with a full pre-season he can get back to the level he was at last season next season where he had finally established himself at centre back for his national team. Long-term I reckon Rojo-Smalling should be the backup centre half pair to either Bailly-Lindelof (if Lindelof can actually achieve the potential some deem him to have) or Bailly-Aldeweireld/Umtiti/whoever we may sign. (Maybe Tuanzebe in the slightly longer term)
4. Jones (26) - Often does top class interceptions and tackles, reading the play excellently. Unfortunately he is not very good in the air defensively, remember choupo moting earlier in the season. He is also is too prone to absolute shockers of mistakes like against spurs. Injury wise this season things went well for him at least till around january/early february, but historically he been injured way too much. Personally I'd sell Jones at the next opportunity to do so.
5. Lindelof (23) - Our youngest established centre back. Undeniably quite good on the ball with his passing out of the back although I find that ball-playing centre backs seem to be more mistake prone. He needs to improve a lot defensively, I not confident in him winning 1 on 1s with attackers at all. The majority of our absolute worst performances this season he has played in, including Huddersfield, Basel, Bristol, West Brom, Sevilla away. I have noticed improvement in him though. Hes young for a centre back and he did only just arrive this season, so he needs time and still deserves a chance to prove himself at United. Quoting LVG: "It is a process." Next season is the season where I will judge him more. If he is still having some rubbish performances and not showing enough for me to think he'll ever turn out any good then I might be one who is keen for us to sell him. We need to see more glimpses of his supposedly high potential.
Blind I wasn't sure where to put because its been so long since I saw him play at centre back, his best position imo. I'd sell Blind too.