There is a vast gray area in dealing with the gray matter of the brain, especially on Sundays such as the last, when NFL quarterbacks were seeing stars in three different games.

There is a vast gray area in dealing with the gray matter of the brain, especially on Sundays such as the last, when NFL quarterbacks were seeing stars in three different games.

Michael Vick of the Philadelphia Eagles was hit on successive plays in a game against the Dallas Cowboys. It is not clear whether Vick was concussed on the first or the second hit. What is clear is that he is suffering from a “pretty significant” concussion, the team said on Monday. Say hello to backup Nick Foles.

Jay Cutler of the Chicago Bears took a hit to the head from Houston Texans linebacker Tim Dobbins. Although Cutler was laid flat, he rose and stayed in the game for seven more plays, and it was only at halftime that his concussion was diagnosed. Say hello to Jason Campbell.

Alex Smith of the San Francisco 49ers experienced blurred vision after he was drilled in the head by St. Louis Rams linebacker Jo-Lonn Dunbar. Smith was clearly “dinged up,” as they used to say, but he took 12 more snaps. He even managed to throw a touchdown pass through blurred vision before he was removed. Say hello to Colin Kaepernick.

Football is a tough game played by freakish athletes at crazy speeds. Once a quarterback steps out of the pocket and tucks the ball under his arm, defenders will take liberties. The New Orleans Saints offered bounties. The Pittsburgh Steelers offer James Harrison.

Injuring the quarterback can be a game-changer. Vick, Cutler and Smith each “had his bell rung,” as they used to say, in the second quarter. The Eagles and Bears lost and the 49ers ended up with a tie. It might not be good for business — not even for the bookies — to have marquee players watching from the sidelines, but it is good for the opposing teams.

For all of this, there was something more fundamentally disturbing about Sunday’s carnage. Vick, Cutler and Smith stayed on the field after taking shots that should have raised red flags. What about the NFL’s concussion protocol? It is fair to wonder whether it is accepted as a critical endeavor or a mere nuisance.

Here, we enter the gray area. Concussions are mercurial by nature. Symptoms can be subtle and take time to surface. In another game on Sunday, Buffalo Bills running back Fred Jackson absorbed a late hit, an elbow to the back of the head from New England Patriots linebacker Brandon Spikes. Jackson did not display symptoms — headache, amnesia, confusion — until the flight home.

The concussion issue has come to the fore as long-term implications have become better understood. The NFL’s hand has been forced by class-action lawsuits in the name of thousands of former players, some of whom are experiencing early-onset Alzheimer’s or other degenerative brain conditions. In the notable cases of Dave Duerson and Junior Seau, the psychic pain was such that they shot themselves in the chest and donated their brains to neuroscience. These incidents and others have increased awareness, and the league has promised continued action. Improved diagnostic procedures are crucial because the next concussion almost is always worse than the last.

Cleveland Browns fans well recall what happened with quarterback Colt McCoy, who found his head in Harrison’s crosshairs last December. McCoy was removed for two plays after the helmet-to-helmet hit, went back in the game and lobbed an interception. Afterward, his father, a high-school coach in Texas, lashed out at the Browns for not protecting his obviously concussed son. The NFL heard the message, clearly, and put certified athletic trainers in the press box and video feeds on the sidelines to better track potentially dangerous hits.

For what it is worth, the league reviewed what happened on Sunday with the Eagles, Bears and 49ers and found that the three teams followed established protocol. What else can be done?

Football culture is such that players often will not divulge symptoms. The next step for the NFL is to add independent neurologists into the real-time diagnoses, continue to adjust its protocol and invest in the development of new equipment.

Someday, technology might allow for instant and definitive calls on concussions, but that day was not Sunday.

Michael Arace is a sports reporter for The Dispatch.