The Post Sports Live crew tries to figure out the missing element from the Capitals that is preventing them from playing to their full potential this season. (Post Sports Live/The Washington Post)

Over the course of an 82-game season, rarely does one contest perfectly encapsulate the strengths or weaknesses of any team, but Tuesday night’s devastating 5-0 loss to the Dallas Stars certainly showcased the Washington Capitals’ continued lack of defensive aptitude.

Upon being named coach in June 2012, Adam Oates stated that he wanted a team built on a foundation of crisp puck movement and clean exits from the defensive zone in order to push the pace up ice. As he approaches the end of his second season behind the bench, though, Washington has yet to achieve that goal.

The Capitals are a mistake-prone bunch when it comes to puck management and often make decisions that don’t take into effect developing plays, but Oates says he sees slight progress.

“At times yeah, at times no,” Oates said, playing down the significance of Washington’s repeated blunders. “You are going to give up chances, we chart it every night. . . . Every single night there’s a different breakdown, but we’re the same way [in creating chances] the other way.”

But there’s a difference between giving up chances and melting down when doing so, as the Caps did on Dallas’s second goal. Ray Whitney scored on a two-on-none rush that occurred because one defenseman tried to force an offensive play and then went off for a bad line change, and the other blue-liner inexplicably lost track of his surroundings.

Dmitry Orlov held the puck in the neutral zone but rather than put it in a place where none of his opponents could get it, he chose to try to thread a pass through to Mikhail Grabovski. Instead, it wound up on the stick of Stars netminder Kari Lehtonen, who sent the breakout the other way.

“When you make the pass and it actually goes through you look great, but when the team gets the puck then it looks bad. It’s just simple things,” said Jaroslav Halak. “Those are little mistakes we could just get rid of and not make moving forward.”

Then Orlov went off for a change, rather than sticking with the play, which Oates saw as the biggest misstep. At the same time, Mike Green — one of 14 players who has rotated through the blue line, including eight that had played fewer than 100 games heading into this season — missed two Stars players lining up behind him. By the time the stretch pass from the Dallas zone hit their sticks, and Green was alerted to their presence, it was too late for him to recover.

“I honestly didn’t know there wasn’t somebody beside me. Had I known or taken a look — I’m accountable for that too, I should have looked over,” Green said before blaming the change. “The pass probably wouldn’t have been made cross ice if someone was there.”

The Stars’ second goal came 34 seconds later from a complete debacle on coverage assignments as three players — John Erskine, Julien Brouillette and Chris Brown — marked one opponent while leaving another wide open down low. It was a familiar situation in which the Capitals were caught scrambling, out of position.

While the damage came quickly on that occasion, Washington often spends extended stretches trapped in its own zone chasing the play and possession, which results in giving up an extremely high volume of shots.

The Capitals average the sixth-most shots against five-on-five per game of any team — 31.3 — and the highest amount in any season since they began reaching the playoffs in 2007-08. Over that same seven-year span, Washington’s shot differential at even strength has plummeted. At the high point in 2008-09, the Capitals had a plus-313 shot differential. It had steadily declined since and this season it is minus-206, also the worst in this seven-year sample with the same core players.

The defensemen aren’t alone in their lapses, either, as most of Washington’s forwards have lacked urgency to help out in their own zone. An egregious example came in the loss to the Stars, when Alex Ovechkin glided at the offensive blue line and neutral zone as Dallas charged toward the Capitals’ net.

Ovechkin didn’t even notice Whitney until the veteran winger had raced past him. Only then did Ovechkin take a forceful stride, but pulled up just two steps later.

“Ovi quit on the play coming back,” Oates said. Whitney “forced [the play] down the ice and just goes to show you you’ve got to hustle the entire time, the whole entire time.”

But when Washington’s top players, and in this case the face of the franchise, aren’t holding up their defensive responsibilities, it questions the ability of the entire group to actually dedicate itself to playing a solid game in its zone.

“We want to do that, but it obviously isn’t going our way, especially for top guys in the defensive zone. We’ve been scored on a lot and that’s not good. That’s not going to win us games,” Nicklas Backstrom said. “For me the effort’s not there, and we’re not working tight together. That’s something we need to get better at; we need to make everyone accountable.”

Capitals notes: Washington signed one of its 2013 second-round draft picks, defenseman Madison Bowey, to a three-year, entry-level contract Wednesday. . . .

Chris Brown was reassigned to Hershey of the American Hockey League.