However, the Dane admits he expects a lot more from the former RB Leipzig midfielder as he adjusts to Premier League demands.
He said after the 3-0 win: "I think he was promising. I liked what I saw from him. I liked that he took initiative on the ball. Every single time he had the ball he tried to create something.
"And I think he had a wonderful assist for the first goal from a corner. Worked hard as well. I think it was a good first game."
Frank, meanwhile, admits fellow new signing Joao Palhinha will need time to adjust to his system.
"I think we need to - even though he's played in the Premier League before - it's still a new club, a new coach, crazy new ideas from the coach, all those things. And then he had a little disjointed pre-season because he played at the Club World Cup, without playing too many games, or barely any.
"So I think he will grow and be better. Happy again with his performance today. Solid. He just gives the team that structure and solidity."