Jerod Mayo did not realize his the quarterback was in danger.

At 1:09 of the first quarter, Drake Maye was hit on the back of the helmet by Jets linebacker Jamien Sherwood while sliding. The rookie got back up and was on the field for four more plays, including a pass attempt and a sack.

At this point, the Patriots I didn’t realize Maye had suffered a head injury. Eventually, the sideline received a call from the NFL saying the Patirots’ No. 3 pick needed to be evaluated for a concussion. This led to Maye’s exclusion and eventual exclusion from Sunday’s win over the New York Jets.

On Monday, Mayo explained what happened after the play.

“I didn’t know. I was surprised when (Jim) Whalen told me he had to go to the medical tent,” Mayo said during a morning news conference with media. “He then threw some good balls. I thought he was still pretty sharp in that regard. Obviously, it’s above my pay grade to take him out of the game and put him in the protocol.

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At the conclusion of the 2011 NFL season, the league implemented the use of independent certified athletic trainers to work as concussion observers. Their job is to operate the video injury review system monitor as well as review the football of the game. If they see a play that could have resulted in a concussion, they will call the team bench to speak with the athletic trainer.

Once the player is removed from play, medical staff conducts an evaluation and must remain consistent with the NFL’s “return to play” protocol.

On Sunday, that’s what happened with the Patriots and Maye. That’s why their coach, Whalen, told Mayo the team needed to evaluate the quarterback.

“It was overturned by the league. They wanted to do a more thorough evaluation,” Mayo said on WEEI’s “The Greg Hill Show.” “When I went in there at halftime, he wanted to go back, but obviously he didn’t pass the test. And I’m not going to go too far into that. But, at the same time, he went out there and threw some good balls after, I guess, supposedly putting it in the protocol.

Since Maye was diagnosed with a concussion, he was unable to return to the game and could not return to the field until he passed the NFL’s five-step concussion protocol.

Before Maye can return, he will have to go through five phases. The first phase is where a player can perform limited stretching and light aerobic exercise without experiencing any symptoms. Next, the player begins progressive cardiovascular exercises, dynamic stretching and balance training. If he has no symptoms, he moves on to Phase 3, which consists of soccer-specific drills in which a player performs a sport-specific drill for 30 minutes or less.

If Maye has no symptoms, he will move to Phase 4. This includes non-contact football activities such as throwing, catching and running. If he has no symptoms, Maye will move to Phase 5, which includes full football activity, including contact. At this point, the player should be examined by an independent neurologist.

If that doctor agrees that Maye’s concussion “is resolved,” he can participate in the next practice or game.

“At this time, Drake is still in the NFL concussion protocol,” Mayo said Monday morning.

Will Maye be away for a while?

“I’m not sure,” Mayo said on WEEI.