That is according to former Arsenal, Leicester and England striker Alan Smith.
Jose Mourinho won three Premier League titles in his two spells at Chelsea as well as the FA Cup and League Cup a combined four times.
However, the Portuguese has been unable to find such success at his second club in England – Manchester United.
His long-term future at Old Trafford is uncertain after four defeats in the first 12 league games of this season.
And Smith says a reason for Mourinho’s struggles is that he does not quite have the same spark he had during his time at Chelsea.
“Basically he’s not the coach that he was,” Smith said on Sky Sports.
“I think that’s glaringly obvious.
“He doesn’t seem to be the personality that he was and that personality would drag players with him through a brick wall which he famously did with Chelsea.
“(Frank) Lampard and (John) Terry still eulogise about his managerial powers.
“And he does appear to have lost that.”
Smith also says there seems to be no comparison between the impact Mourinho has had on his Manchester United players and Pep Guardiola on his at rivals Manchester City.
“The contrast with Guardiola is striking,” Smith added.
“When you think of Raheem Sterling, the way he’s brought him on as a player.
“There is a number of performers in that City team that he’s worked really hard on.
“They were good players to start off with, but things are happening at City that just aren’t at United.”