Mike Mitchell's aggressive behavior toward Charcandrick West and Alex Smith will cost him.

NFL Network Insider Ian Rapoport reported Thursday that the Steelers safety was fined $48,620 for his hit on West and $9,115 for his hit on Smith, the Chiefs quarterback, per a league spokesman.

Mitchell's tackle came late in the third quarter on Sunday as Smith climbed the pocket to avoid an initial blitz from the Steelers defender. Smith subsequently checked down to an open Kareem Hunt, who caught the pass, before Mitchell -- a full second later -- closed in to take Smith down from behind at the knees.

Mitchell was tagged with a 15-yard roughing the passer penalty for his antics, which left Smith fuming.

"I felt like it was extremely late," Smith said Tuesday. "I felt there was nothing done there to avoid contact. It was really low from the backside. I thought it was about as flagrant as it gets when it comes to a low hit on the quarterback."

Mitchell's hit on West came with two minutes left in the second quarter.

The league clearly agrees.