The former Socceroos goalkeeper and long-time Tony Popovic assistant worked closely with the 44-year-old in the duo's brief spell at Karabukspor.
Although it ended dismally for Popovic, who was sacked after three wins and six losses, Kalac maintains that the Aussie coach did little wrong and it shouldn't hamper his reputation.
“It was overall a good experience, other than how it panned out in the end," he told The World Game.
“And a lot of that was based on the political turmoil within the club.
“It wasn’t to do with our work, which was very good. Poppa made some important, positive changes there. He had the team training and playing the right way but luck didn’t smile at all on us.
“There was also a huge political in-fight happening at the club and we were caught in the middle of that a bit.
“The way we left was disappointing and that was part and parcel of the situation there, which has worsened since our departure.
“Our intel told us prior to going they had never been late with a payment.
“It’s not a matter of us knowing better because we weren’t to know. It was impossible.”
Popovic may have to wait for another European opportunity, but there will be no shortage of interest in Australia with three A-League clubs - including Sydney FC - currently without long-term coaches.
While a move to the Sky Blues would be controversial for the Western Sydney icon, harnessing Australia's biggest club at the moment could spark a renenewed surge in Popovic's career.
At least, if other countries will take it seriously.
“People will say I’m biased but in my view he’s top notch and I’ve worked under some pretty good coaches," Kalac said.
“This season you had Arnie talking about winning the ACL, but you have to win a game to get out of the group first. People think it’s easier that what it is.
"I think Poppa will coach at the highest level ... but he has to get past some difficult perceptions in places like Europe.
“Over there the opinion is ‘you’re Australian, what do you know about football?’.
“We live in a bubble here and all we have is the A-League and that doesn’t count for much in Europe."