In the past, many departing managers have been forced to sign no poaching deals with their clubs as part of the compensation package. For instance, Liverpool's Brendan Rodgers did this when he was negotiating his exit from Swansea last summer.
That kind of recruitment block can be imposed if a manager is under contract when prised away by his next employer. Moyes' contract with Everton expires on June 30 so he can't be tied by any restrictions by the Goodison Park club.
Both Everton stars Leighton Baines and Marouane Fellaini have been secured by long-term contracts but Fellaini has a £20million buy-out clause in his deal, while Baines would cost about £15m. Those prices would not deter United.