Revis, a perennial Pro Bowl player, sustained a mild concussion when he was kicked in the head by teammate Bart Scott in Sunday's win over Buffalo and was diagnosed Monday. He was cleared for noncontact practice but has not been cleared for contact.
Ryan said the decision to sit him Sunday was a medical decision. Kyle Wilson will start in Revis' place.
"We'll always follow NFL protocol when it comes to concussions," Revis said. "I'm doing tests every day, doing the best I can to get back." He added Friday that he feels better and continues to improve.
This is the first concussion Revis has had, so he said the protocol he is following is unfamiliar to him. He practiced with the team Friday for the first time all week, in noncontact drills only.
"I felt good, it felt good to get out there," he said.
Neither Revis nor Keller nor Thomas will travel trip to Pittsburgh. Keller pulled a hamstring in the third preseason game and aggravated it Wednesday in practice. He was not on the field Friday, and the team signed TE Dedrick Epps to the active roster to fill his roster spot. Ryan said he hoped Keller would be able to play in Week 3.
"The guys that step up and replace a guy have to maintain that level or even a little better," Ryan said. "In this case we'll take a little less, with the Darrelle Revis deal.
"It's just best that (Keller) sit out, miss this game and then hopefully be ready to go next week," Ryan said.
Thomas also has a hamstring injury and worked off to the side Friday. Although Thomas after practice expressed a desire to play, the Jets determined he wasn't ready. Garrett McIntyre will fill Thomas' role.