Grugier-Hill told reporters Thursday that he suffered a head injury on the first play against the Miami Dolphins in Week 13 and lied to the medical staff so he could stay in the game, saying that he had hurt his shoulder.
When the symptoms failed to subside, he came clean with the team the following Thursday. Grugier-Hill was placed in concussion protocol and missed last week's game against the New York Giants.
"This goes back to training camp when we sit in here as a team and have a medical meeting and we disclose to our players and we stress how important it is for our players to, one, either self-police themselves and/or a teammate, kind of say something to a medical team member [about something] of this importance," Pederson said.
"We know how important head and neck injuries are to our league and to just the player himself and the well-being of the player. And so from that standpoint, to have this come back like this and for him to admit what he has said and done, is very disappointing for me as a head coach after putting our players through meetings and instructing our players.
"It's not a reflection on the team or anything like that, it's just one guy who made a bad decision, a bad choice. I take football aside. I say, hey, this is a well-being issue. Had he maybe gotten hit again in that game, who knows what could have happened."
Grugier-Hill has since been cleared from concussion protocol.
Pederson said he has not yet decided whether to discipline Grugier-Hill. He noted that standards have changed in the NFL, and with an ongoing effort to protect not just players but the sport of football, there is less room than ever for this kind of action.
"In a sense it's a little bit of a selfish act to take it upon yourself and make that decision when he could have gotten checked out and, by the way, probably would have been cleared to go back in the game at that point," Pederson said. "I'm disappointed."
In other injury-related news, Pederson said that Alshon Jeffery will undergo surgery in the near future to repair a Lisfranc injury. Pederson did not commit to a recovery timeline.