DENVER — One of the first players to walk out of the Browns locker room after Sunday's 29-12 loss at the Denver Broncos wasn't even on the active roster for the game.

Sunday likely will be the last time Joe Flacco's not on the Browns active roster. The recently-signed quarterback was not elevated from the practice squad to the gameday roster for the Denver game.

By the next time they play a game, next Sunday in Los Angeles against the Rams, there's a very good chance Flacco will be on the active roster, be it as an elevation or a full-time addition. There may even be a chance he's the one the Browns starting against the Rams.

What remains unknown is the long-term impact of the head injury rookie starter Dorian Thompson-Robinson suffered during the third quarter of Sunday's loss. The only thing head coach Kevin Stefanski could confirm was that he had, indeed, suffered a concussion when the Broncos' Baron Browning delivered a hit to him right after he released a pass on the next-to-last play of the quarter.

Stefanski didn't comment on the nature of Browning hit. However, the former Ohio State Buckeye outside linebacker denied trying to injure the Browns QB.

“I didn’t think it was a dirty hit, but they called it," Browning said. "So what can I do about it?”

What do the Browns do to deal with yet another quarterback injury? Stefanski is maintaining the same answer for Thompson-Robinson as he did when it was Deshaun Watson, who ultimately went from a rotator cuff sprain in October to season-ending shoulder surgery this past Tuesday.

“Yeah, that's just part of the game," Stefanski said. "Injuries are part of the game. A very unfortunate part. We'll see how Dorian does here but that's part of it.”

P.J. Walker, the only other quarterback on the active roster on Sunday, came on for the injured Thompson-Robinson. Walker, who started a pair of games and finished out another while Watson was recovering from a rotator cuff strain in October, was 6-of-13 for 56 yards while being sacked four times, including for a safety.

Walker played just two snaps with the Browns still in a one-score game. By the time he attempted his first pass with just over 12 minutes remaining, the Broncos were up 24-12 and pinning their ears back on defense to rush the passer.

“That is tough," Walker said. "They know we are automatically in passing situations. It is hard to go out there and execute like that at that time in the game when you are trying to drive the ball down the field. They know you have to pass the ball, so it is hard to do it. You have to take advantage of the opportunities when they do present themselves. I was not able to do that today.”

Thompson-Robinson, much like the previous week against the Pittsburgh Steelers, had been up and down throughout against the Broncos. He finished the game 14-of-29 for 134 yards with a touchdown and a 73.1 passer rating.

"It's tough seeing the work Dorian puts in," receiver Cedric Tillman said. "Like you said, me and Dorian, I felt like we was connecting. We was looking to build off that in the second half. Unfortunately he got hurt. So sometimes that's just the way it goes."

There were drives where he seemed locked in, such as when he went a combined 7-of-13 for 96 yards with a touchdown over the Browns' final first-half drive and their first second-half possession. Those two drives ended with the Browns scoring a field goal to pull within 14-6 at halftime, and a touchdown to get within 14-12 with 6:42 remaining in the third after Amari Cooper dropped his 2-point conversion pass.

There were drives like the one in which he got hurt, where he was struggling to find the rhythm. On the play that knocked him out of the game, he took the snap at the Browns 23, but scrambled to the point he was near the goal line before he threw a pass.

The pass never had a chance to get caught. The flag, which didn't come at the moment of impact, but after Thompson-Robinson was on the ground for a moment, gave the Browns a new set of downs.

It also gave the Browns another quarterback injury issue.

“It is tough," Walker said. "I thought DTR went out there and played a hell of a game today. He showed his toughness. It is just tough with a concussion. You cannot really call that injury, but it is tough. The bug is going around the room. We are just trying to find ways to do it. That is what we have been trying to do the past couple weeks is overcome adversity.”

Chris Easterling can be reached at ceasterling@thebeaconjournal.com. Read more about the Browns at www.beaconjournal.com/sports/browns. Follow him on Twitter at @ceasterlingABJ

This article originally appeared on Akron Beacon Journal: Dorian Thompson-Robinson's concussion adds to Browns' QB injury issues