The Rangers defense has changed dramatically within just one week. 

K’Andre Miller was placed on injured reserve on Friday with an upper-body injury.

He won’t join the team for the start of its three-game road trip, which starts on Sunday after Saturday’s clash against the Kings at home, and is required to miss at least seven days. 

Miller exited the Rangers’ 3-2 win over the Sabres on Wednesday with the injury, though it’s unclear when it occurred.

He was hit hard by Jordan Greenway in the second period but he continued playing the rest of the period. He then didn’t come out for the third period, though. 

Coupled with the decision to trade Jacob Trouba to the Ducks, the Rangers have now lost two players who were considered defensive mainstays right as they try to get their season back on track. 

“I think everybody goes through it over the course of the year, where they have to count on the depth within the organization,” head coach Peter Laviolette said after practice on Friday. “We feel like we have good pieces in place to come up when it’s their turn to step up.” 

Connor Mackey skated with Braden Schneider on the second defensive pairing — where Miller had been skating recently before his injury — during Friday’s practice.

The expectation is that Mackey will replace Miller in the lineup, Laviolette said. 

Mackey has yet to play for the Rangers this year and appeared in one game last season.

In 22 games in the AHL this season, he has two goals and four assists and is plus-two on the ice. 

“He was good, the times that we had him up here,” Laviolette said of Mackey. “He’s a big, strong, reliable defenseman. He played heavy and physical, he moves the puck, he did a pretty good job for us last year. 

“We have confidence. He’s going to play some good minutes. We’re counting on him.” 

In that sole appearance last year, a 7-2 win over the Senators on Jan. 27, Mackey got into a memorable fight with Ottawa star Brady Tkachuk.

Mackey got the better of Tkachuk, landing a few clean blows and eventually knocking him to the ground.

The Rangers were trailing 2-0 at the time but subsequently scored seven unanswered goals. 

Listed at 6-foot-3 and 205 pounds, Mackey’s size is what most stands out about his game. 

“He’s a big boy,” Schneider said. “We play quite similar games. He plays a north, hard, physical game and I think we’re going to have some fun. We’re going to make sure we’re hard to play against and keep things simple.” 

Mackey was with the Rangers for most of training camp and was one of the last players to be sent down to Hartford as the team trimmed its roster. 

He now has another chance to prove his worth in the lineup. 

“It was hard, for sure,” Mackey said. “But it’s a business. Down there, just worked hard and had a positive attitude and tried to continue to get better was kind of my focus each day. Still doing that right now.” 

Miller and Trouba had both been struggling. 

Miller, the Rangers’ first-round pick in the 2018 draft, has two goals and four assists this year and is a minus-five on the ice.

Trouba, while with the Rangers, had no goals and six assists and was minus-three on the ice. 

And their struggles were central to the Rangers’ regression this season.

The Blueshirts have given up far too many chances, relying on goalie Igor Shesterkin to constantly bail them out and keep them in games.

For the season, the Ranges have given up 893 shots on goal — seventh-most in the NHL entering Friday. 

Perhaps the need to shake up the team’s defense actually can be a blessing in disguise. 

“If we can continue to clean that up and keep playing the tight hockey that we have been and limited chances that we’ve been giving up, it’s definitely a recipe for success,” Schneider said. “I still think we can do a bit better job of limiting those big chances.”