The typical Manchester United CB is 6ft3 is physically strong, he's good in air, he's not injury prone, he's not a slow poke, he's got decent positioning & passing ability. Stam, Vidic, Rio, Johnsen and Pally were like that. We did tried to change that with Mickey (too short), Blind (way too short), Jones (short and injury prone) and co. The results were devastating.
So what do we need?
A- We need to acknowledge that formula and stop trying reinventing the wheel. Hence Tuanzebe, Rojo, Bailly, Jones and Lindelof will never make it with United. At least not at first team level.
B- We need to buy players whose skill set cover for Maguire's deficiencies. Thus we need a 6ft3 CB whose fast and has got decent positioning. He need to be physically strong but he don't need to be a rock either as Maguire is that player. Also we can get away with a CB whose not an excellent ball playing player and whose not a great leader. All those skills are provided by Maguire as well.
In my opinion we should sell the lot I mentioned, we should retain Smalling and we should sign Badiashile and Magalhaes for a combined fee of around 60m-70m. For those saying that 2 CBs is over kill here is my response
A- I'd rather have 2 CB with the POTENTIAL of becoming estabilished CBs. Then 4-5 CBs whose got no chance in hell of making it with us.
B- Maguire and Smalling are established CB. Smalling might not like being a reserve but he is indeed under contract, no one is offering decent money for him and I'd rather keep him for a year to make sure at least 1 of the new guys make it then throw him out on the cheap.
C- We would be recouping most of the money by selling those lot, most of whom are either too shit or injury prone to be useful even as reserves.