The Dutch defender emerged at AZ as a youngster, but did not get any first team chances.
He eventually moved to Voldenam and then Wolfsburg before getting his big Premier League move to Spurs.
Postecoglou told reporters this week, as his team prepare to take on AZ in the Europa League: “With Micky, fair to say he developed late but very quickly. Because I think even at Volendam, there was a period when they were unsure about him.
“You could tell once physically he grew and the kind of player he was, his journey went very quickly at Volendam and the year he had in the Bundesliga he adjusted really well.
“For us last year he was outstanding in his first year in the Premier League. Obviously he had an injury which set him back a little bit but he's growing all the time, maturing and I think he will become more of an influence at national team level.
“He's now played a couple of games at left-back, left centre-back, The more he plays with the national team will give him even more belief but he's going very well and I'm sure he'll be an important member of our team but also the Dutch international team.”