McDavid gave Edmonton a 7-1 lead when he scored on a penalty shot with 3:33 left in the third. After being tripped by Pittsburgh defenseman Brian Dumoulin, he went forehand to backhand and back to his forehand for a shot around DeSmith.
Letang scored on a power play with 1:48 remaining for the 7-2 final.
The Penguins were outshot 44-24, including 14-3 in the first period.
"It's frustrating right now," Letang said. "We're not playing the way we were supposed to play. We get discouraged pretty quick."
NOTES: McDavid, who had seven shots on goal, had at least four points for the ninth time this season, becoming the first player to do so since Mario Lemieux (16 games), Jaromir Jagr (nine) and Peter Forsberg (nine) in 1995-96. McDavid is the only Edmonton player in the past 30 years to have a goal streak as long as Draisaitl's; he scored in seven straight from Nov. 28-Dec. 9 this season, and six in a row from March 28-April 7 last season. … Pittsburgh had two goals disallowed in the third period. Evgeni Malkin thought he scored on a power play at 2:28 before it was deemed offside during an Edmonton challenge; Jeff Carter used a high stick to deflect a puck in at 8:25. … Dumoulin was minus-3 in 15:43 of ice time.