Seems to me Jose suffers from a managerial form of ADD. New projects are what he needs to get the best out of him. When he steps into a new job, he has the greatest effect but his mind games & tactics eventually have diminishing returns. I'd think his 'Golden Age' when it comes to longevity at 1 club was when he had SAF, Rafa, & Arsene to cut & parry with, but now he's a bit bored with holding the hoodoo over Arsene, while Pellegrini & LVG are at best medium term foes and are less likely to engage in verbal & mental games as the above.
When he was in the picture to possibly be SAF's successor, I thought he might've grown past it, but apparently it seems he hasn't. Heck, even Pep seems to have a similar propensity in that once he's finished his 'revolution', it's time to find new challenges. Let's be honest, Mou has basically conquered most of his challenges, and all that is left is the Bundesliga & maybe a World Cup. Maybe a run with PSG might tickle his fancy, but I doubt it.
His current bad run with Chelsea is a bit of a shock, though. Not sure if he's lost some players or whether his tactics have been too rigid & other teams have caught on to him, but Chelsea should have more than enough to get better results.