When asked about his unnecessary roughness penalty shortly after last week's 12-10 preseason loss to the Chargers, Vikings rookie safety Harrison Smith said, "There's stuff that sometimes you can't control."

The NFL disagrees. And it's going to cost Smith a $21,000 fine when he gets his first NFL paycheck next week.

The hit on Chargers receiver Mike Willie came in the closing moments and extended the Chargers' game-winning drive. The nature of the hit made it probable that Smith would be out some money once the league got around to reviewing the matter.

"He unnecessarily struck a defenseless player in the head and neck area with his shoulder," league spokesman Randall Liu explained in an email.

After the game, Smith tried to describe the split-second thought process that comes with playing safety in a league that's making it more difficult for defenders to hit offensive players.

"I thought maybe I could go for the ball, then I realized I should go for the hit, so I kind of got caught in the middle," Smith said. "I wish I didn't get the penalty. Maybe I could have played it differently. I'll watch the film. It's easy to watch on TV and say, 'You should hit him here or there. ... At the end of the day, football is football."

Smith brings speed, size, instincts and a nasty edge to a position the Vikings have struggled at for years. This might not be the last time he gets a letter from the league following a big hit.