Well, straight from the horse's mouth - he claims that he has a better team at spurs than the one he had at United. One might ask him, how it came to be this way, after he spent half a billion euros on players at United, but I have no problem taking his word that it's true. It probably is a better squad and certainly a better fit.
Also, this prematurely talked about 'title challenge' will depend to a large extent on whether or not City or Liverpool continue to struggle as they have. If that remains the case, it's not just a lower points total to chase, but a significant psychological boon to everyone else including spurs.
Once you consider those two factors, they alone are enough to explain away why a title challenge might be possible, whereas previously it wasn't, without having to resort to fatuous interpretations like 'the game has passed him by'; 'football has moved on' and other such tripe that then necessitates further brilliant analysis like 'he has reinvented himself'; 'a new man!' etc.
Jose is still Jose. Still a cnut, and now that he has all but described himself as such, maybe his United days sycophants can stop taking exception to the rest of us calling him that. Still an excellent manager too, but also a flawed character, and he will deliver dour, reactive football with some regularity. If you're a spurs fan though, you obviously take it.