Without inside knowledge, it's hard to say why Levy et al (as presumably the board and Lewis had input) decided 'arry had to go. People here have said why they would have sacked him.
We've seen some strange appointments and sackings across the EPL - most look odd from the outside. But 'public' appearance tends to hide any friction that may be happening behind the scenes.
The motive will probably never be known, until biographies / autobiographies surface.
I just hope the board's next appointment keeps up the momentum that we appear to have gained over the past few seasons. It's easy to make a rick as we've seen with AVB (and a whole raft of managers) at the Chavs, and lately with 'kin Kenny at Pool (although I don't like Dalglish, I wasn't sure that his squad was good enough to do much better than they did anyway - they played very well at times, and at times looked appalling). Then a manager like Pardew, looks initially an odd / unpopular appointment at Newcastle and turns out to be a gem
Whoever Spurs do appoint though, the man has got to be given time to show what he can do, so you're looking two or three seasons away to be able to really judge anyway.