Spurs led in all three games but, amid injuries, suspensions and plenty of wasteful finishing, failed to take any points as their high line and failure to make their pressure pay opened the door for their opponents.
However, Ardiles is adamant that Postecoglou must persist with his attacking style.
"Ange is going to persevere with his philosophy of football and I believe that is absolutely crucial," he told Reuters.
"The approach that we had against Aston Villa, it was absolutely brilliant.
"We were there to win the game and this is what Tottenham always represents and this season is going to carry on being like that."
Ardiles, who won the FA Cup twice and the UEFA Cup at Spurs as well as the 1978 World Cup with Argentina, spoke highly of Postecoglou's off-pitch changes to a club that limped home outside of the European places last season.
"Since the moment he arrived, Ange has been a breath of fresh air in the club," the 71-year-old added.
"He has changed everything. The atmosphere in the club was not that nice, to be perfectly honest, and he changed immediately all that.
"He has done a wonderful job in a lot of respects, but especially the connection between him, the players and the supporters."