Winning trophies is not the only measure of success.You do realise that Mourinho has outperformed Klopp for the large part of his time at United.
To be a successful manager you have to win trophies. Klopp hasn’t.
Improving players and improving the team, then creating an attractive and exciting way of playing is also a measure of success.
Its only a matter of time before Klopp wins another trophy.
The only trophy that I can see on Uniteds horizon is the Championship Trophy a few years after they get relegated.