There was such a difference in performance and mentality that the confidence on the pitch also made it seem like it wasn't a big match.
This season is likely to be the worst season for Spurs if you look at the last 1 decade of Spurs' journey in the EPL, which has always been in the comfort zone in the standings, this season is the worst point for them.
Fortunately, this season we have got 3 clubs that have certainly been relegated this season because if not, the situation will be very dangerous considering that currently the Spurs are even thrown into 16th position, which is quite a jump from what they got in previous seasons.
I think there needs to be a comprehensive improvement for this and it could be that with a situation that is indeed severe as it is now, Ange Postecoglou is likely to lose his position as coach next season.
I really do agree with you here because so far I haven't seen Tottenham in such a position before, infact I haven't seen them the season like this before since I started following football. It's not just that's hit with this bad performance, Manchester United is also in this same boat. Just like you said, if a team like Leicester City and Southampton weren't in the position they found themselves this season just maybe Tottenham would have been one of the teams to be facing relegation this season.
Their stats over the last 20 years show that they are really, really bad as this season is their worst ever.
For some other clubs like Southampton or Leicester actually they are quite reasonable for me because indeed in the last few seasons they have always been constrained in the transition in the EFL and EPL but now for Tottenham they are really bad where they can't even develop the pattern of the game because Ange Postecoglou seems confused with what they have to do even though some of the players they have are still quite qualified but it cannot be denied that when the scheme does not go well and the players lose mentality makes them now at their lowest point since the last 20 years.