The Pittsburgh Penguins entered this weekend in postseason position, winners of six straight and scheduled to face a couple of non-playoff teams. It all sounded great.

In practice, it couldn’t have gone worse.

The Penguins scored only one goal in two games and fell 1-0 to the Bruins in Boston Sunday night, concluding a forgettable weekend that saw them fall out of playoff position.

While the Penguins did make a push in the third period, they were never able to pull even and were outplayed most of the game. Of glaring significance, the Penguins were short-handed six times against the Bruins.

Viktor Arvidsson scored the game’s only goal when he outworked Erik Karlsson for position in front of the net and beat Stuart Skinner. Bruins goalie Joonas Korpisalo was perfect, stopping all 27 shots he faced.

Skinner continued his run of stellar play, stopping 17 of the 18 shots fired his way. The Penguins goaltender has now allowed one goal in each of his past four outings. That performance, though, wasn’t enough to earn a victory.

The Penguins rarely threatened during the first two periods because of how often they were short-handed.

“It was a lot of time on the penalty kill,” coach Dan Muse said. “It makes it hard. It’s a lot of minutes for a small number of players, and a lot of (other) players aren’t getting into the flow of the game.”

Sidney Crosby was robbed on a couple of strong backhand looks late in the second period, but otherwise, there was nothing going for a Penguins team that was again playing without the injured Bryan Rust.

“They make it hard to get to the net,” Muse said. “We could have done a better job with our execution to get into the zone more, and to generate more traffic in front of the net. That part of our game has been better as of late, but today it took a step backwards.”

The Penguins won only once in a 10-game span entering the NHL’s holiday break, but returned to action and immediately won six games in a row. Now they’ve lost two straight. They’ll attempt to snap this losing streak when they return to action on Tuesday at PPG Paints Arena against the high-flying Tampa Bay Lightning.

Ten postgame observations 

• Rust’s absence from the lineup is becoming a growing concern.

It’s not just the Crosby line that is affected when he’s out. On Sunday, there was a trickle-down effect that changed three of the four lines, and I think this is a problem. There was no fluidity in the Penguins’ attack during each of the past two games. There was no semblance of chemistry. Really, there was no offensive action to speak of at all.

Rust has long been among the most important Penguins and that has not changed. The team is pronouncing him “day to day” and the Penguins had better hope that is indeed the case.

• I have agreed with most of what Muse has done with the Penguins this season. In general, he’s been terrific. However, in my opinion, when he’s been wrong, he’s been wrong, and the decision to play Kevin Hayes at second-line center was ridiculous.