Defenseman Kevin Shattenkirk (22) has 42 points in 61 games in 2016-17 — three shy of his career high. (Jeff Curry/USA Today Sports)

The Washington Capitals made a major move Monday night, acquiring top-four defenseman Kevin Shattenkirk and goaltender Pheonix Copley from the St. Louis Blues in exchange for forwards Zach Sanford and Brad Malone, the Capitals’ 2017 first-round draft pick and a conditional draft pick or picks, the team announced. Shattenkirk is expected to be in the Capitals’ lineup against the New York Rangers on Tuesday night.

The move reiterates that Washington is in win-now mode, paying what could be considered a hefty price to reinforce its defensive corps. Shattenkirk will be the third right shot on the team to go along with Matt Niskanen and John Carlson, and he can play on the team’s power play.

Through 61 games this season, Shattenkirk, 28, has 11 goals and 31 assists. He will provide the Capitals with an offensive threat from their blue line who will fit in with the league’s stingiest defensive team. Shattenkirk is a rental, scheduled to become an unrestricted free agent this summer, and he was the top defenseman on the trading block. He carries a cap hit of $4.25 million, but the Blues are retaining 39 percent of his salary and bonuses.

Speaking with reporters late last week, Capitals General Manager Brian MacLellan indicated he wouldn’t be making a blockbuster move like this one before Wednesday’s trade deadline. He said any upgrades would be “on the fringes” because he didn’t want to tinker with lines nor defensive pairs on a team that leads the NHL with 89 points.

But with 10 Capitals players in a contract year and the core of Alex Ovechkin and Nicklas Backstrom getting older, MacLellan also acknowledged a pressure to leave no stone unturned in what could be Washington’s best remaining chance to win a Stanley Cup with Ovechkin.

An injury scare to Niskanen last week, which exposed Washington’s lack of top-end right shot defensemen, might have pushed MacLellan to make this move. Niskanen is expected to play against New York after missing three games, but MacLellan acknowledged that the team didn’t have a blue-liner with top-four upside if Niskanen or Carlson went down in the playoffs.

“I think it’s always tough because, ideally, you just like to go with what you have, but if someone gets hurt, it’s like, ‘Well, why didn’t you get someone?’ ” MacLellan said. “I mean, you’re always going to be opening yourself up to that. . . . We don’t have a specific need that we’re trying to address. We’re trying to just say, ‘If something happens, what’s the best way to cover that?’ The insurance.”

But MacLellan added that depth “concerns every team. I mean, nobody has five, six top-four defensemen.” With the acquisition of Shattenkirk, an NHL all-star in 2014-15 and a member of the U.S. Olympic team at the 2014 Sochi Games, Washington now does.

If the move doesn’t result in a Stanley Cup, then the Capitals have left themselves with few top end draft picks in the near future. Though the 2017 draft is considered weak, the team already traded its 2017 and 2018 second-round picks in a trade for center Lars Eller this past summer.

Washington won’t have a pick until the fourth round of the 2017 draft. Sanford was one of Washington’s top forward prospects after the Capitals signed him out of Boston College this past summer, and he has two goals and one assist in 26 games played in the NHL. The Capitals signed Malone last summer, and he has spent the entire season with Hershey in the American Hockey League.

With the Pittsburgh Penguins and the New York Rangers also believed to be bidding for Shattenkirk, trading for him might have been partly about blocking Metropolitan Division rivals and potential playoff opponents from acquiring him.

The trade also addresses the Capitals’ need for a No. 3 goaltender with the acquisition of Copley, whom Washington traded to St. Louis in the deal for T.J. Oshie before last season.

Last week, MacLellan said this is the best team that has ever been around Ovechkin. His move on Monday night made it better.

“I think we’ve tried to create a sense of urgency here, even starting last year that this is it here,” MacLellan said. “You have two years to figure it out, this group. That doesn’t mean that going forward we’re not going to be good, but . . . something’s got to give because of the roster we have. Something’s got to fall out, and I’m not sure what it’s going to be, but it’s not going to be the same.”

Complicated conditions

The conditions attached to the conditional draft pick or picks included in the deal are complicated.

Should Washington sign Shattenkirk for at least next season or advance to the third round of the playoffs with Shattenkirk playing in at least half of the games in the first two rounds, then the Blues get the Capitals’ 2019 second-round pick.

If Washington trades Shattenkirk on or before July 1, then St. Louis will receive Washington’s next available seventh-round draft pick. However, if the Capitals receive a draft pick in return for Shattenkirk in that hypothetical trade that is a fourth-round pick or earlier, then in lieu of that seventh-round draft pick, the Blues will receive Washington’s own next available draft pick two rounds later than the earliest draft pick received by the Capitals in exchange for Shattenkirk.

As an example, if Washington trades Shattenkirk for a third-round pick on or before July 1, when he is set to become an unrestricted free agent, then the Blues would get Washington’s next available fifth-round pick.