MIAMI -- Dolphins quarterback Tua Tagovailoa has been ruled out for Sunday's wild-card game against the Buffalo Bills, coach Mike McDaniel said Wednesday.

The third-year pro has been in the concussion protocol since Dec. 26 after suffering his second documented concussion of the season the day before in a loss to the Green Bay Packers. McDaniel said that Tagovailoa has not been cleared to resume any sort of football activities, and that because of the amount of time he has already missed, McDaniel was able to rule him out.

"I would say it's conflicting," McDaniel said of Tagovailoa's reaction to being ruled out. "He, himself, is learning that he needs to listen to the advice of doctors and medical professionals. He understands the severity of doing that, so there's a little bit of things that he can't control. He was an incredible part of the entire season. I think eight of our wins were as a result of him playing quarterback, among the team, and that did not come because it was just gifted. That was a lot of work and preparation, so it's very frustrating, much as a lot of things in life and football are.

"But it is very frustrating for him to not be able to go through everything with his teammates and really it was a huge goal of his to help get this team to the playoffs and he wants to play in the playoffs. There's nothing more fun than playoff football and he really finds normal football fun. So very conflicting I would say, but [Tua] understands that it's his best interest that the doctors and medical professionals are seeking and respects and regards that."

McDaniel said the Dolphins are preparing for rookie Skylar Thompson to make his third career start Sunday; veteran Teddy Bridgewater is still working his way back from a dislocated pinkie on his throwing hand, and his possible availability is unclear.

At Caesars Sportsbook, the point spread on the game moved from Bills -9 to -12.5 immediately after Tagovailoa was ruled out and was continuing to climb Wednesday afternoon. The line, which opened at Buffalo -11 but dipped down to -9 early in the week, was as high as -13 Wednesday afternoon, while the over/under total dropped from 46.5 to 43.5 on the Tagovailoa news.

Thompson a seventh-round pick out of Kansas State, started the Dolphins' regular-season finale against the New York Jets, completing 20 of 31 passes for 156 yards. He credited the experience for preparing him for a playoff environment.

"The good thing for me, I feel like I got a pretty good feel for what a playoff game kind of would look like just last week," he said. "It was a win-or-go-home-type of situation for us, so getting to experience kind of what that felt like last week I think was helpful. This week is just going to be like any other week for me this entire season. It's preparing like I'm going to be the starter and getting reps where I can build some confidence throughout the week and build continuity with this offense to where when we go out there, we can play fast and play with confidence on Sunday."

Should he start Sunday, it'll mark Thompson's seventh appearance this season, four of which have come in midgame relief of the starter.

McDaniel praised the rookie for being able to keep the Dolphins afloat despite limited first-team reps and experience, and Thompson said his confidence has gradually built with every rep he's taken.

"Honestly, every snap, I feel more and more confident," he said. "It's not always going to be perfect. We strive for perfection in this position, and that's what you want, but in reality, name a quarterback who has ever played a perfect game. For me, it's just dialing in on one play at a time and taking the game as it comes, controlling what I can control, and ultimately just giving it my best, because my best is always enough.

"That's something my former quarterback coach at K-State, Collin Klein, used to always tell me, and that's something that I just remind myself all the time is my best is always enough. I think just moving forward, that's going to be my same mentality and just having fun with it."

McDaniel has not established a timeline for Tagovailoa's return since the quarterback entered concussion protocol Dec. 26. Medical experts advised him that it's "critical" for Tua to focus solely on the day he's in, and McDaniel said he's adhered to that over the past two weeks.

He declined to answer whether any concern has been raised over Tagovailoa eventually resuming his NFL career but said that isn't his primary focus right now.

"I'm just thinking about his day and him getting to full health as a human being," he said. "And then when it's time to turn the page, I'll turn the page, but I'm pretty ... integrity in principle to a fault and stubborn as all get out. If I hear that's the way that I should approach it, I will approach it that way and I do not deviate. Really, the next step is for him to be fully through this protocol and then we can see where the land lays, so to speak. But outside of that, I'm just worried about him."

In other injury news, Pro Bowl left tackle Terron Armstead has progressed after missing the team's past two games with various injuries, although his status for Sunday's game is still undetermined. Running back Raheem Mostert suffered a broken thumb in Sunday's win over the Jets and underwent surgery for the injury Monday. McDaniel did not provide an update to his availability but did say he'd "be a fool if I was the 1,500th guy that tried to tell Raheem Mostert he couldn't do something."

ESPN's David Purdum contributed to this report.