The 55-year-old held back on culling his squad last summer, with Adnan Januzaj and Wayne Rooney the only players to leave, but he looks set to oversee a considerable exodus following this season as he continues his overhaul of the squad.
And the futures of Mata and Herrera, neither of which have nailed down a regular place this term, are uncertain amid reports claiming that Mourinho is prepared to dispense with up to ten players over the transfer window.
And according to Spanish media outlet Marca, Mourinho will not put the pair on the transfer market this summer but is willing to respect whatever choices they make regarding their future.
The prospect of Man United allowing Mata to leave makes little sense considering the club activated a one-year extension clause on his contract in January. Mourinho’s claim that he would not make any further attacking signings this summer also seems to suggest that he sees Mata as part of his plans.
And Herrera is a likewise curious case. Surely the boss would be reluctant to let the Spaniard, despite his dip in form this season, head for the exit door along with Marouane Fellaini and Michael Carrick for fear of a dearth in midfield options next year.
You sense Mourinho would only acquiesce to Herrera’s departure if he had already lined up a like-for-like replacement to come in over the transfer window – something that, quite frankly, needs to happen regardless of what the Spaniard decides to do.