Wolves were in the Championship when the 39-year-old had a brief six-game spell at the Baggies in the 2005/06 Premier League season.
Since then Wolves have returned to the top tier of English football and qualified for the Europa League.
And as he prepares his side to face Wolves in the Europa League on Thursday night, Kozak spoke of the change at Molineux.
He said: “Since the last time I played here (in England) there were more home local players. There has been more money put in, more sponsors and also more players from abroad.
“So, better quality, more professional and it (Wolves) is definitely a top league club with good players. We are very pleased to play them, (they are) such a good team.”
Nuno Espirito Santo’s side beat Slovan 2-1 in the reverse Europa League Group K clash.
Slovan were originally ordered to play the game at the Tehelne Pole behind closed doors.
UEFA fined and sanctioned the Slovak champions after fans made racist chants in a play-off game against PAOK of Greece. But UEFA rules allowed accompanied children aged 14 and under to attend, with the game a 20,000 sell-out.
Now 1,000 Slovan fans are expected to make the trip to Molineux for their fourth group game.
And after only 200-plus made the trip to Braga and the fans were unable to watch the home clashes with Besiktas and Wolves, Kozak feels they deserve this away day.
He said: “I’m really glad that we have got such great support. The fans they deserve such a good match after such a long time in Europe. They will definitely help so I can only say on behalf of us that we will do the maximum that we can to play well.”
Aleksandar Cavric, David Strelec and Moha are all doubts for the clash due to injury.
And Kozak says Wolves’ 1-1 draw with Arsenal in the Premier League showed their qualities and weaknesses.
Kozak is prepared to shift formation, or deploy more strikers to deal with Wolves.
He said: “We have to have a couple of systems.
“We have two systems and maybe more strikers.We (could) try a 3-5-2 or 3-4-3, we will see tomorrow.
“Every team is better when they play at home and they will be well supported by their fans.
“It was confirmed (at Arsenal) that Wolves are of a good quality.
“They had about 25 attempts - which is a big number.
“It just shows how good they are, hey can punish every single mistake and we have to be focused.
“They have made some mistakes too, so we can hopefully punish them too.”