Whilst I agree with that I think there is no point in buying a DM and keeping both Fred and McTominay so may be we should sell on of the two who is saleable to fund the acquisition of a DM. Because if we get a back up to Matic it means that one of the two won't be playing much football and that would affect his value.
The same also applies with a CB, if we are buying a starting CB that means we'd have Maguire, new CB, Lindelof, Bailly and Axel. Presumably Jones and Smalling are goners which should bring us another £20m which would help in funding the signing of the CB.
So all in all we should have a situation where the club wholly funds the signing of Sancho and implements a one in one out policy with the rest. For example we could get £60m from the sell of Fred, Rojo, Smalling and Jones and could sign someone like Rice with that or Koopmeiners for £30m to £35m then supplement the purchase of a CB for around £40m with loan fees for players like Sanchez, Lingard etc.