The Australian coach was dismissed by Spurs last summer despite guiding the club to Europa League glory and has now questioned their direction after the dismissal of his successor Thomas Frank on Wednesday (11.02.26).
Speaking on The Overlap's Stick to Football podcast, Postecoglou said: "Obviously, they've [Spurs] built an unbelievable stadium, unbelievable training facilities.
"But when you look at the expenditure, particularly in the wage structure, they're not a big club. I saw that, because when we were trying to sign players, we weren't in the market for those players."
The coach also felt that the club's mentality is a problem and was puzzled that executives decided to change tack after ending their 17-year wait for a trophy.
Postecoglou said: "That was the thing I was trying to break. My whole thing about winning something in my second year, I was doing that for the club.
"Nobody internally would dare say that because they were too scared, they'd been close a few times.
"Then you break that by winning something and what do you do? You tear it all up and you start again. That's the curiosity, what are you trying to achieve?"
Postecoglou explained that the financial restrictions at Spurs meant he missed out on signing stars such as Antoine Semenyo and Marc Guehi.
He said: "At the end of my first year, when we finished fifth, for me, OK, how do you go from fifth to really challenging? Well, we had to sign Premier League-leading players.
"But finishing fifth that year didn't get us Champions League, we didn't have the money. So we ended up signing Dom Solanke... I was really keen on him, I really liked him. Then three teenagers (Archie Gray, Wilson Odobert and Lucas Bergvall).
"I was looking at Pedro Neto, [Bryan] Mbeumo and Semenyo at the time, Marc Guehi, because I said we need... If we're going to go from fifth to there, that's what the other big clubs would do in that moment.
"And those three teenagers are outstanding young players. Brilliant young players. I think they'll be great players for Tottenham, but they're not going to get you from fifth to fourth."
