Januzaj was very, very young at the time, so I'm not really talking about him.
I'm talking about the younger players that were in and around the time during SAFs last couple of years, obviously DDG was young but also we had Smalling, Evans & Jones in defence all of whom at different stages had looked capable of stepping up alongside Rio/Vidic. Rafael was still only 22/23 and coming off of his best season for the club. Welbeck wasn't going to be prolific but was becoming an important part of the squad & obviously we had signed Zaha as well. There were critical players who were still in their primes at the time like Carrick, RVP, Evra. Hernandez was scoring regularly too & there was also Rooney although everyone knows SAF was going to sell him.
The centre of midfield was obviously the big problem and I remember it being a running joke on here.
The players who had been being brought through by SAF & the coaching staff almost all fell off a cliff. Players who previously looked perfectly competent in a side battling at the top of the table fell away massively. That is not normal and I put it largely down to the complete change in staffing & removal of the senior players who had been setting the standards almost entirely within 12 months or so. I maintain that had SAF been there the following season we would have challenged again for the title.