"It feels good," DeSmith said. "Obviously the win is most important, but the shutout's even better."
It was DeSmith's first shutout of the season and fifth in the NHL.
Jake Guentzel, Sidney Crosby and Mark Jankowski scored, and Kris Letang had two assists for the Penguins (17-9-1), who swept the two-game set with their fifth straight win. Pittsburgh defeated Buffalo 5-2 on Thursday.
"We're definitely trending in the right direction," Penguins defenseman Brian Dumoulin said. "We've been playing good hockey and putting ourselves in good spots ... As you can see, we've been in every game, and a couple of these have been some tight games going into the third period. I think we've been getting better in the third period, trying to attack them, play with the lead."
Carter Hutton made 31 saves for the Sabres (6-16-4), who are 0-8-2 in their past 10 games.
"It's hard to describe right now, truthfully," Hutton said. "I don't know what's going on. Obviously I'm accountable too. We're in this as a team, right? It's frustrating. I don't know if I've ever been in this kind of funk at this level. It's hard to take. I'm a pro, we're going to come to work, but we just can't seem to put it together. It's really frustrating."
The Sabres have been shut out three times and outscored 40-17 during the streak.
"I thought we lost our opportunity early in the second period," Buffalo coach Ralph Krueger said. "They seemed to fall back a little on their heels. That's when we got the majority of our shots and were not able to feel and capture that moment. I'm pleased with the defensive effort, but offensively, and with the puck at times, we seemed to just be too complicated, and I'm not pleased with that part of our game. We need to be able to make plays. We've got a lot of guys who have a higher level offensively in them, and we've got to continue to push for that to show itself in the games."
Guentzel gave the Penguins a 1-0 lead on the power play when he swatted in the rebound of his shot in front of the net at 16:37 of the second period.
"That's what we've got to be. We've got to be able to play in this kind of game, these low-scoring games," Guentzel said. "You've got to be able to stay patient, not be high-risk. It's good to find different ways to win. It's nice to know we can be low-scoring and defend hard. And obviously Casey played a great game tonight."