Rosenberg has been playing catch up with his forward rivals all season due to the lateness of his arrival as a free agent in the summer.
"Some players just take a while to settle," Clarke told the WBA website. "I was at Chelsea when Drogba first came. In his first season, he was good but wasn't great.
"It also took Henry a year or so.
"It can take a while, especially for strikers who have to find different ways to find their space in the game.
"But Markus can do that. He is intelligent."