"Unlocking Paul Pogba" has become Manchester United's Schrödinger's cat since 2016.
Simultaneously Pogba can be seen as the best midfielder in the world and an overhyped talent failing to reach his potential. If only multiple United managers could find the skeleton key to unlock him we'd get our definitive conclusion.
The £89m midfielder was supposed to be the transformative ingredient that would lead United back to an era of glory and acclaim.