I think you and I watched a different Tottenham last year. But that's subjective, so all is good.
So here's my opinion, so take it for what it's worth.
The lesson Tottenham ownership somehow failed to learn, after watching club after club after club make a similar mistake, is that "underachieving" has two forms. One is when the roster is playing hard and the results aren't coming. The second is when the players have given up. Tottenham was clearly the former. When you have a solid manager in place and players that still give him effort, then it's time for a roster makeover. That's Tottenham. That's Real last year after Zidane took the reigns. Even though I'm not sold on Ole, that's ManU right now. Compare that with ManU or Chelsea towards the end with Jose. That's not to say Mourinho won't click at Tottenham. But I'm betting heavily that Mourinho's style of play won't go over well with Kane, Son, Alli, Erickson, Moura, and Lamela. Now, Tottenham will be in for a roster makeover, whether they want to or not, simply because their front office didn't make moves for Erickson, Alderweireld and Vertonghen. Unless the unexpected happens, that's about 200M they are letting go on the free that should have been used to bring about a roster change. Now? Their stuck in a financial crunch from the stadium build and having to pay transfer fees to fill slots. Horrible. Just horrible. It's just a matter of time, IMO, until Jose starts complaining about not being able to bring in the defenders and defensive midfielders he wants and marginalizes solid first-team players. It's probably going to get better for about 3 months, then get pretty ugly. But it will be entertaining to see what they do in the summer window to fit Mourinho's style. Of course, if Mourinho changes things up and starts playing attacking football for the first time in over a decade, then all bets are off.