Kevin Stefanski expressed the same level of disappointment and frustration as his other players and coaches Tuesday when discussing his reaction from the Browns' 16-14 loss Monday to the Raiders.

Stefanski couldn't be at FirstEnergy Stadium to coach after he, as well as 19 other players, remained out with COVID-19. That set the stage for a difficult challenge Monday, but the Browns were certainly up for it — they built a 14-13 lead in the final minutes and rallied behind QB Nick Mullens, the third-string QB who needed to start with Baker Mayfield and Case Keenum still on the reserve/COVID-19 list.

Then, heartbreak struck. The Raiders kicked a game-winning field goal as time expired, delivering another punch of disbelief to a team that experienced plenty of that emotion in the previous six days.

"I'm incredibly disappointed with the result last night," Stefanski said. "Very, very frustrating to not come away with a win. 

"(But it's) not a lack of effort from anyone involved. I thought the coaches and players that were out there fought their rear-ends off. I appreciate that, but it ultimately didn't get the job done, and that's what stings the most."

Although the frustration was impossible to push to the side, Stefanski and the Browns couldn't have asked much more out of the numerous backup and practice squad players who were asked to step into heavy roles following a week where the Browns managed just two full practices.

Mullens was front and center of that group. The fourth-year QB veteran has spent the entirety of the season on the practice squad and had just one full practice to prepare for Monday, but he did what he needed to keep the Browns alive by protecting the football and finding first downs in crucial situations. He finished 20-for-30 with 147 yards, one touchdown and no interceptions and overcame a slow first half to give the Browns a real shot at victory.

"He played how I thought he would play," Stefanski said. "He was efficient, he got through his reads, delivered the ball on time and fought till the end. Nick's a grinder."

But Mullens was far from the only player Cleveland needed to step up.

Joel Bitonio, who found out before the game that he was voted to his fourth-straight Pro Bowl as a left guard, started at left tackle for the first time in his eight-year NFL career. Michael Dunn started at left guard. Blake Hance started at right tackle. 

The O-Line didn't allow Mullens to be sacked once.

On defense, M.J. Stewart, who had taken defensive snaps in only four games this season, played every snap as either a cornerback or safety. Jovante Moffatt took his first defensive snaps of the year and played the majority of the game. DT Sheldon Day played his most snaps of the season, too, and DE Porter Gustin, who's spent most of the season on the practice squad, was heavily used on the edge.

"There's a ton of examples of guys playing more than they normally do or playing out of position," Stefanski said. "It sounds easy, but we put some guys in some tough spots, and they fought like crazy. It wasn't perfect at all times, but they were going to do anything and everything they could to try to help us win a game."

Just because the result didn't go the Browns' way doesn't mean they shouldn't be proud of who stepped up, but the team has little time to think about anything from the game now — the next one is already just four days away.

A Christmas trip to Green Bay awaits, and the Browns will have to use every hour available to prepare. The Packers are 11-3 and coming off a win against the Ravens, and the Browns, 7-6 and 12th in the AFC playoff chase, likely need to find a way to win that game and their remaining two others to crack a playoff berth.

The Browns are hoping to also return several of the players who were unable to leave the reserve/COVID-19 list for Monday. Mayfield, of course, is one of them, and so is WR Jarvis Landry, TE Austin Hooper, CB Troy Hill, DE Jadeveon Clowney, S Grant Delpit, S Ronnie Harrison Jr. and both starting tackles, Jedrick Wills Jr. and James Hudson III, among others.

Several of those players, however, will hit Day 10 of being on the list on Saturday, which means they could be eligible to play. Mayfield is one of those players with a possibility. Stefanski is also in that group, and he said the Browns will prepare for those situations accordingly.

"Obviously, the hope is that guys test out sooner than that so that you can get them in the building and get them back going physically, mentally, get them back out at practice and those type of things," he said. "Short of not knowing, we just have to plan on the people who we have and we know about, and then we will adjust based on what occurs over the next couple of days."

More uncertainty is ahead, and the Browns will have to cope with it as they move on from a painful Week 15 result.

"You have to own it, and you have to learn from it," Stefanski said, "but then you really have to move on."