The Blues set their 23-man roster for the opening of the regular season, which will come Wednesday against two-time defending Stanley Cup champion Pittsburgh.

Some were expected to make the team based on their camp performances (forward Wade Megan and defenseman Vince Dunn), but perhaps the surprise of training camp is that 2016 first-round pick Tage Thompson made the cut, and 2014 sixth-round pick Samuel Blais, who had a very solid camp, was assigned to the San Antonio Rampage of the American Hockey League.

The thought was that Blais would make the opening night roster in light of injuries to some key Blues forwards, and that Thompson, who had a solid camp himself, would go down the AHL and get a full season of seasoning in before becoming a full-time NHL player.

But with a season-ending knee injury to Robby Fabbri, Alexander Steen out at least the first week of the regular season with a hand injury, Patrik Berglund being out until December with a dislocated left shoulder and Zach Sanford out until at least late February, the Blues feel Thompson, who turns 20 on Oct. 30, is ready to stick.

At least for the time being.

"It's important to remember and I know 'Army' (Blues general manager Doug Armstrong) mentioned this yesterday that obviously you lose a couple guys," Blues coach Mike Yeo said Monday. "It puts increased focus and urgency on some guys to step up and to be ready. Just because you have that void, doesn't mean all of the sudden they're going to be ready. This is the best league in the world with the best players in the world. We needed to make decisions that we felt were going to give us the best chance going into Pittsburgh and being ready for Game 1. That said with Sammy, the meeting was extremely positive. I am very, very pleased with the development that he's had in a year and the improvement that he's shown through training camp. This is ongoing, the process is ongoing. Right now, they're not as good as we want them to be in the future. The bottom line is we believe if a player's not here to be in our opening lineup off the hop, then we don't want young players around and not have them develop. Obviously it's a long year. Sammy did a great job. He's not with us right now, things can change. Hopefully he goes down there and continues down the same path and we're real excited to see what he's going to bring us in the future here."

Thompson skated on the third line Monday with Magnus Paajarvi and former Penguin Oskar Sundqvist, and could very well make his NHL debut Wednesday.

"We want to make sure that Tage doesn't go in paralyzed by fear thinking that one mistake is going to put him back down in the minors," Yeo said. "I think they have to have some comfort, some confidence that they can play the game. But that said, the reality is whether it's him, whether it's some of the other guys that were in the conversation of who should stay and who should not, the reality is that you have to perform and that's kind of where our group is at. We've got some guys out of the lineup, some guys are getting a chance for me. What we saw with Tage is obviously you see his size, you see his shooting ability, you see his skill level. It's the ability to play a role with a line that's played two games together and looks like an NHL line. They've had an identity between him and Magnus and Sundqvist as far as a line that can be defensively responsible, can eat up minutes by hanging onto the puck in the offensive zone. For me, he's a player that has shown me that he's engaged in all aspects of the game. Every time he's on the ice, he's engaged. If he's in the defenive zone, he's alert. If it's in the offensive zone, he'd involved and that's why he's here today."

Thompson, the son of former Peoria Rivermen coach Brent Thompson, got the news from Armstrong and Yeo on Monday.

"Obviously it's a good feeling," Thompson said. "It was my goal coming into camp. When you achieve that goal, it's a good feeling. There's still work to be done. It's a long road ahead. This was a hard challenge to make the team, but I think the hard part is going to be staying here. We'll see how it goes.

"Obviously you're going up against stronger, older guys. You're going to face challenges. For me, I had a pretty good camp I thought. Luckily, there was not too much adversity I had to face. For the most part, I felt I had pretty strong preseason games. There's things I need to work on, but the staff's there to help me with that, going over things in between periods or after practice or whatever. It's made it a lot easier on myself."

Dunn beats out Walman

Dunn, the Blues' second-round pick in 2015, beat out Jake Walman, who was assigned to the Chicago Wolves of the AHL, for a spot among the Blues' seven defensemen while Jay Bouwmeester (ankle) is out through the first week of the season.

"Yeah, it's a pretty crazy feeling," said Dunn, who was also told Monday morning by Armstrong and Yeo. "Looking back a few years, I probably didn't see myself here, but right now, I think just a lot of hard work and a lot of determination. I finally get my chance and I'm really excited to be a part of the team.

"It's a huge honor to be a part of this club. When you're a kid, you don't really know how fast things come at you. The last few years, a lot of the things to come my way. I'm pretty fortunate for everything that's happened. "

"We talked about right from the start that we felt like there were a lot of strong candidates," Yeo said. "We knew it was going to be a competitive camp and we knew there were going to be hard decisions at the end. We knew some guys might play their way onto the team. We're here today facing exactly what we expected to face. We didn't know how it was going to pan out and what numbers were going to be there at the end. I wouldn't say that we were surprised by any of it.

"Both guys have shown us that they have high-end offensive ability, they're going to add to our organization for a long time. Both are going to have solid careers. For us, what we felt was the difference was probably the play without the puck. I think that both had their moments with the puck, both showed at different times that they have some learning to do and some growth with the puck. I'd say without the puck, Dunner was probably a little more solid and steady and a little bit more reliable and consistent with that."

Megan wins job

Megan is the feel-good story out of this whole bunch.

A 2016 free agent signing, Megan, who played college at Boston University, played impressively at both ends of the ice to earn a spot among the 23.

"It's a pretty good story because he deserves to be here," Yeo said of Megan, a 2009 fifth-round pick of the Florida Panthers. "He earned it. I said as much to him today that a guy when you're drawing up lines and you're kind of placing things and who might be here for the start of the season, I didn't think that Wade would be here. I believe that he could be depth and a guy that can definitely fill in and play some games for us given what he did for us last year, he changed our minds, and he did that with his play. ... That type of persistence deserves to get rewarded. We didn't give him any favors here. We didn't do anything for him because it's a feel-good story. He made the team and he did that by playing at a real high level and we're happy for him."

Blues lose out on Jagr

The Blues were among at least two teams that showed interest in future Hall of Famer Jaromir Jagr, but on Monday, the 45-year-old Jagr informed the Blues he was taking a one-year contract from the Calgary Flames for a reported $1 million in base salary and $1 million in signing bonuses.

Armstrong didn't want to comment on it but confirmed the Blues did make an offer to Jagr, who has 765 goals and 1,149 assists in 1,711 NHL games.

"Obviously when we discussed 'Jags,' he's got a lot of points," Yeo said. "Offense was a huge part of it, a guy that can control the puck and maybe he's not the fastest guy in the league, but he has the ability to get in the offensive zone and hang onto the puck.

"It didn't work out and now we're concentrating on our group."

It was reported that the Blues' offer was similar to what the Flames offered, but St. Louis didn't jump into the discussions until Fabbri went down. The Flames have been interested since free agency opened and there's a better chance to play in Calgary, and perhaps Jagr feared that when the Blues get some of their injured guys back, it would diminish his role.

Schwartz, Sobotka flip spots

The Blues ran their lines on Monday in what could very well be their opening night lineup:

Vladimir Sobotka-Paul Stastny-Vladimir Tarasenko

Jaden Schwartz-Brayden Schenn-Dmitrij Jaskin

Magnus Paajarvi-Oskar Sundqvist-Tage Thompson

Scottie Upshall-Kyle Brodziak-Chris Thorburn

Extra forwards included Ivan Barbashev and Wade Megan

Defensive pairs included:

Joel Edmundson-Alex Pietrangelo

Carl Gunnarsson-Colton Parayko

Vince Dunn-Robert Bortuzzo

Nate Prosser was the seventh defenseman

Schwartz had been skarting with Stastny and Tarasenko, but Yeo wants to see things evened out among his top six while Steen is out.

"A little bit of balance," Yeo said. "We'll see how that goes. Obviously we know we can go back to that. Stastny, Schwartz and Tarasenko has been a line that's been real effective in the past for us. I also think that 'Schwartzy' and 'Schenner' had a lot of chemistry together early in camp when we were using them together. We're going to need depth and we're going to need balance, we're going to need scoring from more than one line and hopefully this takes hold and we can stay with it longer than just the one game here."

Sundqvist has, for the time being, beaten out Barbashev as the team's third-line center for what Yeo described as a variety of reasons.

"His play has just been at a higher level," Yeo said of Sundqvist. "We've had a few conversations with 'Barby.' For me personally especially, I have a ton of trust in 'Barby' and belief in him as a player and confident that he'll come around, but his level of play isn't what we would all remember from last year right now. We have to get that back, we have to find a way to get that back and we addressed some areas and some ways that we can do that. What it comes down to is 'Sunny,' he won that spot because he's been a little bit more reliable in his defensive play, a little bit more consistent in his overall play, his faceoffs have been very, very good. His penalty killing has been very good. When you look at the role of what we sort of need from that line, he's been able to fit that."

Kostin begins season injured

Rookie Klim Kostin, the second of two first-round picks in 2017, sustained a lower-body injury on Sunday and will miss 7-10 days.

Kostin begins the season on the injured, non-roster list along with Berglund and goalie prospect Luke Opilka (hip).

"He's done a nice job," Yeo said of Kostin. "It's hard to believe that he's only 18 years old. Certainly has a lot of development in front of him, but you can see the tools are there."

Kostin will remain in St. Louis through the 7-10 days and Yeo said they'll then decide what corresponding move to make.

Yeo confident Allen ready to go

Goalie Jake Allen, who will start the season-opener against the Penguins, has the confidence of his coach that he's ready to go despite a shaky start on Sunday's preseason finale, a 4-3 loss to the Washington Capitals.

In that game, Allen allowed four goals on only 21 shots, including a game-tying goal in the third period on a weak backhand from the high slot by John Carlson that got through Allen's pads.

"I think I'm confident that Jake will be ready to go right from the start," Yeo said. "I think timing-wise and some things during the game, I think are not quite there, but I think that he's ready to dial it up. I've seen enough in him to know and to feel confident that he's going to be ready to step into that level. I think there's a few games where whether we had younger lineups or a little less predictable play in front of him, I would say that he was not at that same level we saw last year but I saw enough when we had the good lineups in front of him and that predictable structured play that he's used to in front of him that he'll be ready for Game 1."

Steen skates again

Steen has been able to keep up with his cardio while being out of the lineup; he skated again on Monday after skating at least twice before team practices last week.

Steen was injured on a non-slashing call on the first preseason game at the hands of Dallas' Antoine Roussel.

"We'll take it this week that he is not going to play and then we'll take a look at it next week, but he's obviously getting closer," Yeo said of Steen. "He wants to get in the lineup and he's doing everything that he can. Conditioning-wise, he's feeling good, he looks good and it's just a matter of things taking its course here."