My 1st choice RB would be Rafael as long as he is fully fit (prefer to leave Fabio as LB to play him when Evra needs resting/out of form).
The problem is that, unfortunately, both the Da Silva twins are very brittle indeed and constantly pick up the slightest knock and are subsequently out of action for weeks. That's why we are having to consider the likes of Smalling and Jones for the RB position, which they can both execute very well in my opinion.
Because of this problem, i feel Sir Alex would prefer to go with - Jones Rio Vidic Evra - as his starting back four. This isn't a bad thing in any case, it just means that it'll leave 2 of Rafael, Fabio, Smalling on the bench. (As, usually, we have 2 defensive subs so one of these 3 would miss out completely, likely to be one of the Da Silva twins).
Another thing is that we have missed the impact of Vidic greatly, when he is present the likes of Rio and Evra are a lot more calm & composed and seem to make less errors when we have Vidic in our settled back four, even the GK's would feel the impact Vidic offers when playing behind such an influential player.
Hopefully, after the international break, when it comes to Swansea (Away), we should 'hopefully' have all our defense back and then Sir Alex can start to prioritise the back four and choose a more settled one consisting of the four defenders he deems most influential to the squads overall success.
I'm just thankful that we have such a 'plethora' of top quality defenders to pick from. Based on ability, i'd be quite content to play Fabio at LB to give time off for Evra as he has looked 'not with it' recently (just a shame Fabio is brittle). As i would also be content to do the same with Rio to give him rest and opt for Smalling at RCB instead.
Both Jones and Smalling have exceeded my expectations since joining Man Utd and it's a blessing to have them as cover bearing in mind the brittleness of the Da Silva's and the fluctuating form of Rio.
This is the way i see things at present, more-so in what i believe Sir Alex would prefer to choose rather than my own choices (in order of 1st, 2nd, 3rd choice defenders) -
RB RCB LCB LB
Jones/Rafael/Smalling - Rio/Smalling/Jones - Vidic/Jones/Evans - Evra/Fabio/Evans
(1st) (2nd) (3rd) (1st) (2nd) (3rd) (1st) (2nd) (3rd) (1st) (2nd) (3rd)
I still think eventually Sir Alex will opt for placing Evans as a left back as he will inevitably struggle to get a consistant run of games being 3rd choice in the pecking order behind Vidic and Jones at LCB. Also, Evra can't go on forever (and Evans struggles more often than not in the centre of defense, just not commanding enough), so i also think it'll be done to accomodate that, so it would be Fabio and Evans alternating at LB once Evra has seen his best days behind him (looks like we are seeing the start of it this season so far.....hope i'm wrong!)
For our next game, and providing these players are fit & healthy i'd go for - Rafael Rio Vidic Evra (2 or 3 of Jones, Smalling, Evans, Fabio on the bench.)
What i think Sir Alex will opt for in our next game, providing they are fit & healthy are - Jones Rio Vidic Evra (Smalling & Evans/1 of the Da Silva's on the bench).
Whichever way, they both look good to me and i'm sure any other team in the league would love to have the defensive options/cover we have on offer, no doubt about that. Once we have a settled back four we will be back to our best i'm sure (4 clean sheets already apparently since the loss to City in the league.....great to have Vidic back, don't underestimate his positive influence on the GK, Rio, Evra and the whole team collectively. On a selfish note, Vidic retiring from Serbian duty can only be another positive for United, he obviously felt the time was right and Man Utd will reap the benefits from that decision (aswell as himslef physically!).....roll on our next game!