When Manchester City announced the appointment of Pep Guardiola, it came in the form of a note passed to reporters at the end of a Manuel Pellegrini press conference in February 2016.
City and Pellegrini decided not to extend his contract, and they moved swiftly to appoint Guardiola, even if it meant potentially undermining Pellegrini's final four months in charge. In one statement, effectively, Pellegrini went from manager to caretaker as all eyes turned to Guardiola's arrival in England.
It was a more structured handover than we're seeing at Manchester United now, who appointed Ralf Rangnick until the end of the season to give them time to find the right man. Even with news that Erik ten Hag has been interviewed over the vacant job, it seems United still don't know who that right man is.