The Ducks are searching for why their second-period play is so less energetic than the other 40 minutes.
One thing they learned for certain in a 5-2 loss Friday is that committing such a dip against a team such as the Pittsburgh Penguins is too much to overcome.
By giving up three goals to the visitors in a span of 9 minutes 6 seconds in the second period, the Ducks (42-18-7) saw their four-game winning streak end.
Opponents have now outscored the Ducks, 80-65, in the second this season.
"It's not our best period. We're trying to figure that out, really don't have any answers for it," Ducks forward Corey Perry said after scoring his 28th goal in a third-period charge that was too late.
Penguins forward Blake Comeau found the net first, sending a deep shot that whizzed off the glove of Ducks goalie Frederik Andersen at 9:51 of the second.
Patric Hornqvist, a nemesis of the Ducks, upped his career goals total against Anaheim to 10 in 21 games with two goals Friday.
He slipped a shot from the left rear side of an unaware Andersen, the puck banging off the goalie's backside to the net.
Hornqvist then positioned himself in front of Andersen and redirected a blast by defenseman Ian Cole that sneaked in with 1:03 left in the period.
"If we knew why we don't play as well in the other periods, we'd correct it," Ducks Coach Bruce Boudreau said. "It happens. It gets in your head. Surviving the second period seems to be what we have to do to win games."
In the third, the Ducks were down, 4-0, after Andersen gave up Evgeni Malkin's 28th goal — he extended a points streak to seven games. Returning NHL most valuable player Sidney Crosby contributed an assist and an empty-net goal.
Recently acquired Ducks forward Tomas Fleischmann scored his first goal for Anaheim to get his team on the board at 9:03 of the third. It was his 11th career goal against the Penguins (37-18-9).
"They stuck with their game plan and maybe we let off a bit," Ducks forward Emerson Etem said. "Last 10 minutes of the third period … if we bring that for the full 60, there's no reason we can't come out with a better outcome.
"But they used their speed, their skill, and there was no surprise it was coming with a roster with two of the best players in the world."
Andersen chalked defeat up to it being one of those nights rather than a testament to Pittsburgh's talent.
"I've got to be better," said Andersen, who's expected to alternate starts through this month with goalie John Gibson (9-5), according to Boudreau. "I don't think about their talent. It's about the things we do.
"You refocus, bounce back, don't get too down on yourself. The only way you get better is game time. Hopefully, I can get back in there soon."
The game marked the return of defenseman Ben Lovejoy, who was dealt to Pittsburgh for 23-year-old defenseman Simon Despres on Monday.
Lovejoy had three hits and was plus-1 in 16:44 of ice time. Despres had six hits, but was minus-2 against his former teammates.