Alex Chiasson skates as Coach Barry Trotz looks on. (John McDonnell/The Washington Post)

After the Washington Capitals parted with significant members of their forward corps this summer in Justin Williams, Marcus Johansson and Daniel Winnik, it was unclear what to make of the options to replace them.

The Capitals had prospects eager to prove themselves in Jakub Vrana, Nathan Walker and Chandler Stephenson. The organization added inexpensive veterans who hadn’t established themselves with their previous teams, such as Devante Smith-Pelly, Alex Chiasson, Tyler Graovac and Anthony Peluso. This mixed bag of seven forwards ranging from a 21-year-old Vrana to a 28-year-old Peluso perhaps has exceeded expectations at training camp, making for some difficult roster decisions Monday.

Washington’s opening night roster has to be set and salary-cap compliant by Tuesday at 5 p.m., and with most of the players left needing to pass through waivers to be sent down to the American Hockey League, the Capitals are expected to have their 22- or 23-man team assembled by Monday afternoon. A 22-man roster seems more likely with Washington’s salary cap constraints, so of the seven forwards still at training camp, four are expected to make the team.

Deciphering which four has been tricky for Capitals Coach Barry Trotz.

“To me, it’s jammed up,” Trotz said.

The Capitals played their preseason finale in St. Louis on Sunday afternoon with a lineup that will closely resemble the one to be deployed in Ottawa in Thursday’s regular season opener. Washington won, 4-3, and Smith-Pelly especially helped his case with a goal and an assist for four points in five preseason games.

Vrana, the organization’s 2014 first-round pick, skated in the top-six forward corps with Alex Ovechkin and center Evgeny Kuznetsov. Though the Czech winger is the only forward left who doesn’t need waivers to go to the AHL, his skill and speed have made him a lock for the team and a candidate to start the year as Ovechkin and Kuznetsov’s linemate.

That leaves three roster spots for the remaining forwards. The Capitals will name two wingers to play with fourth-line center Jay Beagle and carry one extra. Graovac and Smith-Pelly skated beside Beagle in Washington’s penultimate preseason game at Carolina on Friday, while Chiasson, Stephenson and Walker played elsewhere in the lineup. Against the Blues on Sunday, Beagle’s linemates were Chiasson and Smith-Pelly, and other than Vrana, the other roster-hopeful forwards did not play. Peluso is the only one left on the roster not to dress in either of the last two exhibition games, a strong indicator he will be among the group waived Monday.

It’s possible the organization already has seen enough from both Walker and Graovac for them to remain. Both have impressed this preseason, with each scoring a goal in exhibitions. Graovac was traded to Washington from Minnesota in an expansion draft maneuver that allowed the Capitals to add center Lars Eller to their list of protected players. He scored seven goals in 52 games with the Wild last season, and his 6-foot-5 frame with long reach could also be an asset on the penalty kill.

Walker has yet to make his NHL regular season debut, playing in the AHL the past four years. Earlier in training camp, Trotz said Walker and Beagle have similar characteristics on the ice, so they “might enjoy playing together.” The Capitals also would benefit from the speed he can add to the lineup.

Chiasson is with the team on a professional tryout, meaning the 27-year-old doesn’t have a contract for the upcoming season. In preseason games, Trotz has given Chiasson opportunities high in the lineup, playing him with centers Nicklas Backstrom and Kuznetsov and also on the power play, where he scored a goal.

“I wanted to see him with higher-end guys,” Trotz said. “The last couple years, he’s been moved down [the lineup] a little bit, and last year, he had 12 even-strength goals, and you know, that wasn’t too much [less] than top players on our team. He’s got a skill set, and around the net, he seems to pick up some extra goals, and that’s where he’s very, very useful.”

The Capitals signed Smith-Pelly to a one-year, two-way deal in free agency that pays him $650,000 in the NHL and $300,000 in the AHL. Through the first six preseason games, Washington had scored just three five-on-five goals in six preseason games, and Smith-Pelly accounted for two of them, chipping in one in front of the net in Montreal and then notching the primary assist on a Matt Niskanen goal in Carolina. On Sunday, he scored from the crease again, and later his pass sprung Brett Connolly for a breakaway goal, the game-winner.

General Manager Brian MacLellan has referred to the 25-year-old forward as a potential “project” for the Capitals; in 2015-16, Smith-Pelly scored eight goals in 18 games with the Devils, but last year, he tallied just four goals in 53 games, battling a knee injury all season. Smith-Pelly’s upside could make him attractive to another team if Washington exposed him to waivers Monday or Tuesday.

“Do I have it totally clear? No, not totally clear,” Trotz said regarding the final roster spots. “There’s going to be some tough decisions, and the decisions that we make are going to be the decisions that work for us right now and for the organization. And then we’ll go from there.”

More on the Capitals:

Defenseman Brooks Orpik could start season back in Capitals’ top two pairs

With penalty potential high this season, Caps still searching for Jay Beagle’s new PK partner

Capitals power play units are starting to come together

Defenseman Aaron Ness gets long-awaited audition beside John Carlson

Tom Wilson won’t change his physical play because of suspension