The video of Alex Smith smashing into Rams linebacker Jo-Lonn Dunbar replayed several times on Bay Area TV screens Sunday afternoon as the 49ers' medical staff tested the quarterback for signs of a concussion, confirmed their suspicions and then escorted him off the field.
That tackle, so fierce at the moment of impact, seemed the likely culprit. Smith played 12 more downs after the hit, showing no obvious signs of wooziness and throwing a touchdown pass before he went to the sideline as a matter of course. He reported blurred vision once he got there.
Jim Harbaugh would say later that the doctors had not identified the 4-yard run right into Dunbar as the cause of Smith's concussion. "From what I've been told by the doctors and trainers, it seems like it was the quarterback sneak,'' the coach said, referring to a 4th-and-1 conversion that happened exactly five plays after the big hit and six before the touchdown pass.
Smith will now go through specific testing protocols to determine when he can practice and play again. So will two of his quarterback peers, Michael Vick and Jay Cutler, each knocked out of action by a concussion on Sunday.