It appeared as though Josh Allen may have suffered a concussion and perhaps been knocked unconscious during Sunday's 23-20 loss to the Houston Texans after his head slammed against the ground. He was taken to the medical tent for evaluation and appeared to be administered smelling salts.

That made it surprising when he returned to the game, but on Friday, the NFL and NFLPA announced that the proper protocols took place:

Despite the NFL and NFLPA's statement on Friday, the handling of the situation caused a great deal of concern in its aftermath.

"The more I watch this video, the more I'm troubled about what happened," neuroscientist Chris Nowinski, the co-founder of the Concussion Legacy Foundation, told CNN's Brianna Keilar and Boris Sanchez on Tuesday.

He continued:

"As Allen was going down, you see he is raising his left arm to protect his head, which is a very natural movement when you're falling like that, and then after his head bounces so high off the ground, that arm goes limp and you see his wrist catch against the ground which can break your wrist. That's something that any athlete if they were aware would avoid, so I really do think he was unconscious there for a moment after that hit... Ethically, the idea that he was trying to be a hero and no one told him: 'Hey dude, you were knocked out, your teammates had to roll you over' really makes you wonder what happened here and this does need to be investigated."

A number of former players also were critical of how the situation was handled:

Allen said after the game he felt OK following the hit, however.

"Big shot to the chest. Rolled my ankle," Allen told reporters after the game regarding injuries he suffered a play prior to his head hitting the ground. "They flagged me for hitting my head, but felt good enough to go back in."

The Bills also said after the contest that Allen had properly cleared the concussion protocol. The NFL and NFLPA, after reviewing the situation, came to the same conclusion.