I think their problem was when they were beaten by Chelsea and at that moment their mentality immediately fell in the next match. Since the start of the season, their performance has surprised us because they were able to perform better when they didn't have Harry Kane in their squad, but in the last 3 matches, Tottenham experienced a significant decline in performance due to consecutive defeats. Son is playing quite well, he is even one of the players who plays quite an active role in Tottenham front line, but without the right partner he can't do much in the last 3 matches.
When they faced Chelsea, there was a lot at stake as, they were to face a known ally in Pochettino, who has something to prove and worst still, Spurs made a lot of mistakes in that game, caught 2 red cards. I mean, even though Chelsea isn’t at its best, that’s a game they’ve got to win.
Besides, we had Spurs playing high line all through that game and has been catching Sterling and Jackson offside all the time, it was only a matter of time before they figure things out and they did before the goals came pouring.
It wasn’t the same situation for Spurs when they faced Aston Villa today. Can’t say it was a mentality thing for them but, the absence of their play maker in Maddison has got to put the team in deep stress. No one is being that creative no more and Som can only do so much.