Postecoglou joined Tottenham from Celtic ahead of the 2023-24 season, replacing Antonio Conte, and enjoyed early success with his attacking style of play, taking 26 points from his opening 10 league matches.
However, that unbeaten run came to an abrupt end with four defeats in five matches and Tottenham's season tailed off, ultimately missing out on Champions League qualification by two points.
The following season, they won just 11 of their 38 league matches.
Although he enjoyed Postecoglou's style of play, Netherlands international Van de Ven believes Tottenham lacked a "plan B" and revealed he and Cristian Romero discussed taking a more defensive approach with the manager.
"I liked the offensive play [under Postecoglou] but I like what we have now with Thomas Frank. We are more secure at the back. I don't like getting exposed every game on the counter-attack," he said.
"At the beginning [under Postecoglou], no team was used to playing against our system. We were playing unbelievable football.
"But managers analyse everything and people knew what we were doing. Sometimes we didn't really have a plan B and we were getting exposed. We didn't have solutions to get out.
"At one point [me and Romero] walked up to the gaffer and said we need to change some things and play more defensive to make sure we win those games. He was like I agree with you but I expect you two guys to sort this on the pitch, make sure everybody knows."