The NFL and NFLPA are now looking into whether the concussion protocol was carried out properly following a hit to the head of Carolina Panthers quarterback Cam Newton, the NFL announced on Monday.

In Sunday's wild-card loss to the New Orleans Saints, Newton was hit hard by Saints defensive lineman David Onyemata with about nine minutes left in the fourth quarter. Newton came out of the game for one play, was not sent to the specified blue medical tent and then re-entered and played the remainder of the game.

The NFL's statement on Monday reads:

“A joint review by the NFL and NFLPA of the application of the Concussion Protocol following the tackle of Mr. Newton during the Panthers-Saints game is underway. According to the policy developed by the NFL and NFLPA, if the Concussion Protocol is not properly followed the club is subject to discipline.”

Newton said after the game that he was hit in the eye and that he did not suffer a head injury. He remained down on the field before walking off, replaced by Derek Anderson. The Panthers punted after Anderson's incomplete pass on third down, and Newton appeared to be quickly cleared to play again following tests by the team's medical staff. He came back on the field on the Panthers' next offensive series, with 5:08 remaining and the Saints leading, 31-19.

Was the protocol followed to the letter of the law? That's what the league and players' union will seek to find out. Any player showing "gross or sustained vertical instability" following a hit is now required to be evaluated for a concussion in the locker room, according to the NFL's updated concussion protocol.

Newton never left the field. The Saints won the game, 31-26, sacking Newton on the game's final play.

The Houston Texans were reviewed last month when QB Tom Savage re-entered a game against the San Francisco 49ers shortly after suffering a hit that appeared to leave him woozy and shaken. Changes to the league's protocol — including the addition of a centralized unaffiliated neurotrauma consultant at the NFL office to monitor games — were spurred by the Savage hit.

The Seattle Seahawks also were cited for mishandling a hit to their quarterback, Russell Wilson, earlier in the season. The team was fined $100,000 and required to do more medical training as a result. But that price is a pittance for a multi-billion-dollar franchise, so the question of whether the punishment for clubs found to be guilty of not following the rules could become an offseason topic of debate.