Kind of like blaming the academy players for the performances of the senior player.
He was doing his badges here, litteraly learning under, supposedly, more accomplished managers.
I love for ex-players to be part of the coaching staff and I absolutely love the practice of keeping retired players around, expose them to the coaching side of the game and if they re up for it, go prove themselves elsewhere.
Plus such players still tend to have weight in the locker room, and you get the experience and calming influence of a senior player, without sacrificing a spot on the bench.
I'd expect Mata to stay on, " interning " under the next manager and then coach up the youth ranks. And when a managing position comes up, he will go with all our best wishes.
Solskjaer did a great job at the academy level which helped him get a job at Molde and more importantly given him a level of experience that placed him ahead of the other managers in the league, and won Molde first ever title.
Point is, I don't mind ex-players as part of the set-up, if they prove competent for the job at hand. If Guardiola/Zidane were ex-players of ours, you'dnt have anyone complaining were they appointed managers.
Having a history with the club should be a cherry on top so to speak, if the competencies stand up.
