I largely agree with this take, however, I do think AVB put in place a structure that stabilized the results, in his first season I would go into a game very confident of getting the result, bored but confident, as opposed to "swashbuckling" Redknapp's Spurs which when on song was fantastic, but the very next match we could easily still put in a dross performance and get beat by Hull or whoever, (his 2nd season I expected an improvement on the 1st year and hope for a more expansive team, that bit didn't come and he was right to be binned off). But I still think his appointment helped Poch to a degree, as the profile of player (possession capable if that makes sense) brought in under him underpinned some foundations for Poch's team.
TDLR I don't see his appointment as a failure, I see it as an incremental improvement in the squad and a low-bar or basic possession side.
The truly worrying aspect of his tenure is just how random his appointments have been: No two managers share the same philosophy to the game, in many of those cases they are polar opposites to each other (even though I think AVB's possession game and squad building helped Poch, AVB's football was more like his mentor's Mourinho). This reeks of lack of planning, it's a massive concern and I think it's unsustainable to run the football side of the Club like this.
IMO he's backed his managers, he's provided them the environment in which they want to work, so that meant ditching Comolly because Redknapp didn't want to work under/with a DoF, he I think did the same with Poch and Mitchell. But all this does is exaggerate the potential for what has happened under the dinosaur and also will now complicate the recruitment of a replacement.
What philosophy does this team/squad/academy play under now? What is the identity of Tottenham? Who owns it?