Personally I think it's right for Villas Boas to go. Spurs were playing so poorly, and when you invest as heavily as they have, it's inevitable you're only going to last so long when there isn't even a redeeming feature in your style of play. I believe a good manager would have this team higher in the league, playing much better football.
The players they've signed are mostly overrated, but there's enough talent between them to have at the very least improved their standing relative to other teams. Being absolutely clobbered by teams that haven't spent anywhere near as much as you, no matter the gross or net (even though over the last few years Spurs have been in the top 2/3 pretty for net spend) persuasion, is going to raise serious questions.
I think Andre's case is pretty opaquely one where you look almost solely at him, rather than the squad not pulling their weight. He dropped in-form players, persisted with tactics that weren't working, and just stood on the touchline like a squid watching the world go by. We knew from his Chelsea tenure he was utterly stubborn and single-minded, and that's fair enough when you're successful, but it was so evidently not the case this season, that he made himself look moronic.