Washington has lost six of its past nine games. (Steve Roberts/USA Today Sports)

After the Nashville Predators scored for a fifth time, on a brilliant spin-o-rama goal from Rocco Grimaldi that didn’t exactly reflect well on Pheonix Copley, Washington Capitals captain Alex Ovechkin skated the length of the ice to give his goaltender an encouraging tap on the pads. It was shaping up to be a rough Tuesday night for the entire team — but especially Copley, who wouldn’t be getting the benefit of a mercy hook from his coach.

In one of Washington’s worst losses of the season, the Capitals were routed by the Predators, 7-2, to drop their third straight game. Their lead in the Metropolitan Division has evaporated — the Columbus Blue Jackets have pulled into a tie with 59 points — and this can officially be considered a midseason slump. Washington has lost six of its past nine games, and it scored its first five-on-five goal (courtesy of T.J. Oshie) in three games when there was less than four minutes left in the third period. The Capitals already trailed by six at that point.

“When we’re on our game, we’re one of the best teams in the league,” center Lars Eller said. “I’m confident that we can beat any team in the league when we’re on our game. Lately, we have not been on our game.”

Goaltender Braden Holtby was initially scheduled to start against the Predators, but after a stick got through his mask and clipped him in the left eye Saturday night against the Blue Jackets, the Capitals decided to play it safe with his health. A team spokesman said before the game that Holtby was capable of playing, which is why he was available in a backup capacity for a second straight game, but “the club is being extra cautious with him as he fully recovers with his injury.” After the game, Coach Todd Reirden said the team learned just a few hours before puck drop that Holtby “wasn’t going to be able to play,” and there wasn’t time to recall another goaltender.

That meant Copley was in net for the second time in as many nights, and as the game got lopsided, it meant he was going to stay in net, short of an injury.

“That’s a tough spot to put a young goaltender, in a back-to-back situation when maybe things aren’t going his way,” Reirden said. “Obviously, we gave up too many chances, but there were times you probably would’ve made a change, and that was not something I was able to do this evening.”

Capitals defenseman Michal Kempny (6) pokes the puck away from Predators left wing Kevin Fiala. (Steve Roberts/USA Today Sports)

Copley’s teammates didn’t exactly make things easy on him. Playing on tired legs after hosting the St. Louis Blues on Monday, the Capitals allowed far too many odd-man rushes in the first period.

After a Tom Wilson cross-ice pass in the offensive zone failed to reach its intended target, Predators defenseman Mattias Ekholm got possession and sprung Viktor Arvidsson for a breakaway with a stretch pass. Arvidsson scored 3:45 into the game for a 1-0 lead. Predators center Nick Bonino added to the cushion 10:33 into the period, finishing on a two-on-one opportunity.

Bad met worse less than two minutes into the second period when defenseman P.K. Subban’s shot from the point was deflected in front by Arvidsson for his second goal of the game. Offense generated in front of the net like that is something Reirden wanted to see more of from his own team. Coming into Tuesday night, Washington was in a scoring slump with just one goal in each of its past two games and with none coming at five-on-five.

“Today we have plenty of chances, hit lots of posts,” Ovechkin said. “We just move forward. I know it’s a [bad] feeling right now, but nothing you can do. We still have lots of games to bounce back, and it’s nice it happened in the middle of the year and not at the end of the year. I know this group of guys are going to fight for it, and we’re going to be back.”

While the even-strength production has gone cold, the power play has started to turn the corner, a sliver of a silver lining. On the Capitals’ first chance of the game, center Nicklas Backstrom redirected a pass from defenseman John Carlson to cut the Predators’ deficit to two 7:07 into the second period. Washington then controlled play enough to earn another man-advantage opportunity 11:41 into the frame, when forward Calle Jarnkrok went to the penalty box for tripping.

That ultimately cemented the Capitals’ undoing. Just 27 seconds into the power play, Washington turned the puck over on a failed zone entry, and Arvidsson scored on a shorthanded breakaway, prompting hats to hit the ice in celebration of his third goal of the night. The Predators kept piling it on, scoring two more goals before second intermission, including one from Bonino with six seconds left.

The second game of a back-to-back against one of the league’s best teams was always going to be a challenge for the Capitals, especially with Copley forced to play two games in two nights for just the second time in his young NHL career. But that doesn’t excuse how poorly Washington played.

Halfway through the season, the Capitals appear fatigued, perhaps both physically and mentally, after last year’s long run to the franchise-first Stanley Cup ­championship.

When Jarnkrok scored the seventh goal for Nashville, Capitals defenseman Matt Niskanen snapped a stick on the Washington bench, a show of frustration for a team that has looked lost of late.

“Sometimes it’s good to get a slap in the face,” Eller said. “You learn from it and you move on. It eventually makes you stronger and points out some weaknesses that you can work on and just build on. It’s never fun to lose; you don’t want to lose. But these games happen sometimes to every team, and we’ll come back ­stronger.”