He is tactically stubborn and limits himself due to that unflexible approach to things in biggiest games, almost dogmatic (drank his kool-aid too much in latter years, misusing players in positions or becoming too daring and risky in tactics, just to push boundaries and seem revolutionary). But he has had incredibly successful career with his approach for most part and thats why he is pretty much one of the top few best coaches around in his short career. To keep being successful he needs to adapt his approach to different team/league, and its growing experience, if he will stubbornly persist on same path until it sinks or swims, or can tweak it. But to call him a failure after half a season is a joke (not like he is struggling in his 3rd club in a row like Mourinho), and even bigger joke to not ONLY compare him to absolutely nobodies like Spaletti and Sarri, but to say they are better then Pep now