Revis' status for Sunday's game against the Pittsburgh Steelers is uncertain.
"He seems to be feeling good, but whatever those (test) scores are, apparently that's low," Rex Ryan said. "I'll lean on the doctors and trainers. We'll see how he progresses during the week."
Later, in an interview with ESPN New York 98.7, Ryan said Revis attended Monday's meetings and looked fine to him.
The NFL's protocol on concussions states that a player cannot practice or play until he has been cleared by the team doctor and by the team's independent neurological consultant.
On Sunday, Ryan said Revis had suffered a "head injury." Initially, the All-Pro corner said he was fine, but he went for tests Monday morning and the concussion diagnosis was announced at noontime.
"You can't lose a player like Darrelle and say you're not going to suffer a dropoff in production," linebacker Aaron Maybin said. "He's the best cornerback in the league. But as far as people stepping in to get the job done, we're very confident in their ability."
Revis was hurt on a fluke play in the fourth quarter of the Jets' 48-28 win over the Buffalo Bills. He was chasing running back C.J. Spiller and landed on his stomach after a diving attempt to tackle him. While on the ground, Revis was accidentally kicked in the head by linebacker Bart Scott, who also was in pursuit.
Revis took a few moments to get up and walked slowly to the sideline, where he was checked for a concussion by the medical staff. He didn't return to the game. Afterward, Ryan never mentioned the word "concussion."
Later, Revis was in the locker room, chatting with teammates, but he didn't speak with the media. The team, citing the league's media policy for players with head injuries, declined to make him available to speak. Revis also was off-limits on Monday.
Concussions are a hot-button issue, and the league has directed teams to be cautious with head injuries. Ryan said he will "err on the side of caution," relying on the medical staff.
Revis set up the Jets' first touchdown Sunday with an interception. He also shut down Bills receiver Stevie Johnson, the only player last season to beat Revis for a touchdown.
The Jets would miss him enormously against the Steelers, who have quarterback Ben Roethlisberger and three dangerous receivers -- Antonio Brown, Mike Wallace and Emmanuel Sanders. Nickel back Kyle Wilson, who also had an interception in the opener, would start in Revis' spot.
Revis has missed only two games in his career due to injury, Week 3 and 4 in 2010 due to a pulled hamstring. The Jets won both games, beating the Miami Dolphins and Bills, but the quarterbacks were Chad Henne and Ryan Fitzpatrick, respectively -- neither of whom is in Roethlisberger's category.