The goalkeeper, who had faced challenges while on international duty, delivered an outstanding performance in a goalless draw against Brighton over the weekend.
While Ipswich are still seeking their first Premier League win of the season, McKenna believes Muric can help them stay up.
“This was a big step forward and showed everyone why we brought him to the football club,” said McKenna post-game.
“He’s still in the process of getting up to his absolute best and there’s a lot to come.
“Aro’s ceiling is really high for a goalkeeper with the attributes he has.”