Because of the way he plays, Ben Roethlisberger has never gotten the same calls as traditional pocket passers like Tom Brady, Peyton Manning and Drew Brees. On Sunday, Roethlisberger left the game after Rams safety Mark Barron went low into his left knee, a play that wasn't flagged.

Big Ben will have an MRI on his left knee, but for now his status remains unknown for Thursday's matchup against the Ravens.

Meanwhile, we're left to wonder if Barron's hit was, in fact, illegal. In 2009, the NFL clarified its quarterback-protection rule, which included below-the-knee-hits from defenders on the ground.

From the rulebook, via ESPN.com's Kevin Seifert:

A rushing defender is prohibited from forcibly hitting in the knee area or below a passer who has one or both feet on the ground, even if the initial contact is above the knee. It is not a foul if the defender is blocked (or fouled) into the passer and has no opportunity to avoid him. ...

(1) A defender cannot initiate a roll or lunge and forcibly hit the passer in the knee area or below, even if he is being contacted by another player.

(2) It is not a foul if the defender swipes, wraps, or grabs a passer in the knee area or below in an attempt to tackle him.

FOX Sports analyst and former NFL VP of officiating Mike Pereira thinks Barron should have been flagged:

Speaking to reporters after the game, coach Mike Tomlin said he didn't have a problem with Barron's hit.

Wherever the league comes down on this won't magically fix Roethlisberger's knee. Which means there's some chance that the Steelers will host the Ravens and Michael Vick could be their starter.

How long the Steelers will be without Big Ben remains unknown. (CBS)
How long the Steelers will be without Big Ben remains unknown. (CBS)