Arsenal fans have joked about this for decades.
But I seriously believe that Ange Postecoglou is an Arsenal fan agent hired by Tottenham. He seems to have (as Andrew from Arseblog put it) extreme contempt for Spurs fans (as he should), he persists with tactics even after they have definitively been countered by managers within the same match, and his press conferences are legendarily self-pitying. I swear he's doing a Mourinho/Conte/Pochettino: shitting the bed as hard as he can and waiting for Levy to pay his termination clause.