Roope Hintz scored for Dallas (8-5-0), which has lost three of four (1-3-0). Jake Oettinger allowed four goals on 15 shots before being pulled in the second period. Casey DeSmith made 10 saves in relief.
"It was a big challenge coming up against the team leading the league," Stars forward Wyatt Johnston said. "It was a big game for us, and we obviously didn't come out and play the way we wanted to. But you can definitely learn from experiences like this and just take things from it."
Iafallo gave the Jets a 1-0 lead with a power play goal at 7:28 of the first period, redirecting Namestnikov's centering pass over Oettinger.
"Winning in stretches like that is what you play for and we're having fun doing it," Iafallo said. "But once it's game time, we're ready to rock, so it's a lot of fun right now."
Following a turnover by Stars defenseman Mathew Dumba, Rasmus Kupari made it 2-0 at 10:21, tucking in a rebound at the side of the net.
"They're a great team. It starts from [Hellebuyck]," Johnston said. "You see he's been great, but they're playing well in front of him, defending well, not giving us a lot of opportunities, which obviously makes it easier on him. Overall, they're a great team. It's definitely a benchmark for us to remember this game and remember what level we need to get to."
Iafallo said of Hellebuyck, "Another [heck] of a game. He's making incredible saves and keeping our plays in it and making those defensive plays. It goes a long way and pushes us forward. I think he's having a [heck] of a start, so he's got to keep it going. It's pretty fun to watch."
Namestnikov pushed it to 3-0 at 3:34 of the second, jamming the puck in after his initial wraparound attempt was stopped.
"He was trying to cover it, but I saw it there and just poked at it," Namestnikov said. "Luckily, it went in."
Nikolaj Ehlers made it 4-0 at 7:14 with a one-timer on the power play.
Oettinger was pulled 2:07 later.
"I think when you look at [Winnipeg] and Florida, they've exposed us and we've got to be a lot better, DeBoer said of his team, which lost to the Panthers twice in the 2024 NHL Global Series Finland. "I think we've beaten the teams we should beat, but when we've had opportunities to play the top teams in the league, we haven't risen to the occasion. So that's on us."