SANTA CLARA The National Football League Players Association wants another set of eyes on the field looking for concussions, and when you're talking about such a damaging and far-reaching injury, the more observers the better.
But no injury is as difficult to detect, no matter how many eyeballs are on the field.
Alex Smith's situation last week shows just how fuzzy it can be. On the first snap of what would turn out to be a 12-play drive, a hit by linebacker Jo-Lonn Dunbar seemed to stagger Smith and prompted attention from the 49ers' team physicians, one of whom, Dr. Daniel Garza, is considered an authority on concussions.
They looked at Smith between quarters, determined he was fine and allowed him to continue to play. Six snaps after the Dunbar hit, Smith dove into a pile, where he was whacked by James Laurinaitis and emerged with his vision blurred.
Did the first hit make Smith more susceptible to the second hit?
Yes. Maybe. Who knows?
Smith said the independent neurologist he saw last week said the initial blow probably contributed to the second, but it was impossible to say.
What's more, Smith played another six snaps after the Laurinaitis hit and showed no outward signs, at least none the doctors standing on the sideline could detect. He completed three more passes, including one for a touchdown, and looked sharp. In short, Smith did not seem like someone whose brain function had been altered.
The only one who knew something was wrong with Smith was Smith.
Despite his vision problems, the 49ers quarterback didn't want to leave the game in mid-drive. Only when he got to the sideline, sat down and realized his sight was getting worse did he inform coach Jim Harbaugh. Smith subsequently was pulled from the game.
The scenario underscores how unreliable players are at revealing they have a problem.
Some won't tell anyone. Smith's refrain three days later was that he notified Harbaugh only when he realized his lack of vision would hurt the team. He also had a concussion last season but didn't tell anyone about his symptoms until after the game.
Linebacker Brian Urlacher, whose Bears squad visits Candlestick Park on Monday, last week reiterated his stance that he would lie about a concussion to keep playing.
Dr. Catherine Broomand, a neuropsychologist who runs Kaiser's Youth Sports Concussion Program in Sacramento, sees hundreds of patients a year.
She said it's not always machismo or sense of duty that compels players to stay in the game. Often, they don't think they have a concussion because the symptoms don't manifest themselves immediately, sometimes not until the next day.
"It's not entirely that they don't want to come out of the game," Broomand said. "It's that they don't think it's that bad at the time."
Finally, concussed players can be terrible sources as far as their conditions precisely because they've been concussed and their judgement is impaired. Asking a concussed player if he can play is like asking a drunk person if he can drive.
Still, Broomand says she has seen positive steps when it comes to detecting concussions in young athletes. Parents and coaches are becoming more aware of symptoms, and, perhaps best of all, so are the kids themselves.
"A lot of the parents are telling us, 'It's not the coaches that noticed that my kid had a concussion it was a teammate,' " she said.
In that way, some of the best diagnosticians in the NFL might be the 10 other guys in the huddle.
While physicians on the sideline have the difficult task of looking through a sea of big bodies at a player 50 yards away who is further obscured by a helmet and a face mask, the guys in the huddle know better than anyone how a teammate normally behaves, and they are looking those teammates directly in the eyes.
But even the 49ers' players had no idea Smith was concussed last week.
"I mean, he led a touchdown drive," center Jonathan Goodwin noted. "I think he even changed the play. Nothing seemed off at the time. Sometimes, it's not the easiest thing in the world to spot."