The Australian will be reunited with the midfielder that he sold a year ago to Leicester City.
As Spurs and Leicester get ready to play on Monday, Postecoglou was asked about how Winks has improved since leaving the club.
He stated: “Yes, to be fair to Harry, that decision was kind of made before I got here. It is part of the process of change, as I said last week, it is not about a quality of a footballer because he doesn’t fit.
“There is no point in me coming in and tinkering around the edges. We needed to make significant changes, that’s what the club wanted and that’s what I’ve done.
“The squad has changed fairly dramatically from 12/13 months ago but that’s the reason I’ve came in. At the same time, it doesn’t diminish Harry’s career.
“He has had a fantastic season and is back in the Premier League this year. He is an outstanding footballer. These decisions are often not a reflection of a player’s ability, it is just timing of things and things moving on.”