Even if you go through his social media (I know not the be all and end all, but still) he always gave the impression he really didn't give a shit about Spurs or being a footballer in general. In that interview he did after the Gillingham game he just came across as an arrogant toss pot. All of this culminating in that abomination of a loan at Norwich, and really you'd have to question if he will make it at any level unless he drastically changes his mindset.
Onomah is a bit different, I think its more a case with him that he is proper Spurs and does care, but he was just massively overrated and far too much was expected of him.