He didn't win the league with PSG that year because he was appointed manager in December.
Stale Chelsea? He was here for a whopping 2 years in which he came 1st and 2nd. And we were in the title race until the last 3 matches of the second season.
At Milan he finished outside the CL places once when Milan started to sell all their players. He also famously designed the "Christmas Tree" formation as a result of losing players, which he won the UCL with. So I don't understand this idea of him not being able to change tactics.
If you ask me, most Chelsea fans were rather disappointed when he left us.