U.S. star Landon Donovan says the key to Michael Bradley's astounding growth this season at Heerenveen can probably be attributed to his stunningly steady temperament.

The young American Abroad has wowed observers with a team-best 16 goals for the Champions League chasers, performances that USMNT fans will surely hope translate to the international arena.

"The thing about Mike is you don't worry what you're going to get from him," Donovan told Soccer America. "A lot of times with younger players you see a lot of ups and downs."

"Not with him, and if someone tells him he's great, he won't believe it - He just keeps trying to improve."