Couture had a hat trick and Timo Meier, their other linemate, also scored against the Avalanche.
Couture said he continues to be impressed by Nyquist, for what he's done on the ice and the commitment he's shown to his family this week.
"When you're with an organization for eight years and then you go coast to coast and leave your family behind, not an easy situation," Couture said. "But he's come in and fit in very well and played very well for us.
"Tough situation for him [for Game 3], probably didn't get much sleep. Bunch of flights. I thought he played really, really well under those circumstances."
Nyquist has six points (one goal, five assists) in 10 playoff games this season after he had 60 points (22 goals, 38 assists) in 81 regular-season games, including 11 points (six goals, five assists) in 19 games for the Sharks after the trade.
"He's smart," Couture said. "He's fast. His speed can make up for mistakes that myself or Timo can make and he covers for us a bunch of times with this speed."
DeBoer said Nyquist has been a good fit for the Sharks because of his intelligence and his hockey IQ.
"I've said all along, good players want to play with good players and sometimes there are fits and sometimes there isn't," DeBoer said. "I know Logan likes playing with guys like that, that can find him in holes or give and go and make those little plays through people in order to find room. He plays an honest game. He's been good defensively. He's been blocking shots. I think his defensive game is underrated."
Contributions from Couture, Meier and Nyquist have been needed. The Sharks have been without forwards Joe Pavelski and Joonas Donskoi in the series, each out with undisclosed injuries. Donskoi was injured in Game 6 of the first round against Vegas; Pavelski in Game 7 against Vegas.
"I think [Nyquist] has found his rhythm here in this series," DeBoer said. "It started in the last series, we saw pieces of it in the Vegas series, but I think it's starting to come consistently now, which is important. We needed it.
"With Donskoi and Pavelski out, two guys that potentially are top-nine guys in our lineup, we needed some people to step up and he's one of them."
The mindset for Game 4 will be to keep that kind of momentum going.
"You're up 2-1, we have an opportunity to go up 3-1 instead of having them tie it up," said Nyquist, who had a goal in a 5-2 Sharks win in Game 1 against Colorado. "We know what's at stake. It's a huge game and we'll be ready for tomorrow."