"Yeah, I'm [upset]," Sutter said Saturday. "I wasn't pleased at all tonight."
Jarome Iginla scored two goals and Miikka Kiprusoff made 38 saves to lift the Flames.
"The positives here tonight is that we got two points, our goaltender played very well, the captain scored two goals and we got a goal on our power play," Sutter said. "Other than that, it's wasn't a great game on our behalf. We were fortunate to get a win."
Eric Nystrom, Dustin Boyd and Jay Bouwmeester also had goals for the Flames, who rebounded from a 2-1 shootout loss on Friday.
Francois Beauchemin and Matt Stajan scored for Toronto, which has earned just four points in nine home games (1-6-2) this season.
Maple Leafs coach Ron Wilson was left to explain his team's latest loss.
"At the end of the day, you say it's too much Iginla and too much Kiprusoff," he said.
Iginla and Nystrom scored 16 seconds apart in the first 1:37 -- a pair of goals that starting goalie Jonas Gustavsson probably should have stopped.
That left Toronto trailing 2-0 for the ninth time in 18 games this season.
Beauchemin soon started Toronto on the comeback trail. Niklas Hagman was screening Kiprusoff when Beauchemin one-timed a point shot into the net at 5:24 of the first.
However, Boyd followed up on his own blocked shot and backhanded the puck past Gustavsson at 9:54. That prompted Leafs coach Ron Wilson to replace his rookie goalie with Vesa Toskala, who had a good effort during the team's 3-2 loss in Chicago a night earlier.
Toskala seemed to help calm things down and Toronto carried much of the play for the next 30 minutes, outshooting the Flames 20-4 in the second period.
"They really bounced back," Kiprusoff said. "The second period, we weren't ready for that."
Only one of those shots, a backhanded rebound by Stajan, got behind Kiprusoff.
Kiprusoff has allowed just five goals in his past five starts and is a big reason Calgary ended its three-game road trip with a victory. He sprawled his left arm out to take the tying goal off Mikhail Grabovski's stick late in the second period and turned away Hagman from in-close in the third.
"Thank goodness he was there," Flames defenseman Robyn Regehr said of Kiprusoff. "I thought for most of the first period and all the second period, they were the better team.
"He made great saves. I can't say enough good things about him, he had a tremendous game."
By that point, Iginla had provided his goaltender with a bit more cushion. The Flames' captain scored his 11th of the season after roaring down the right wing and beating Toskala high at 2:30 of the third period, giving Calgary a 4-2 lead.
Calgary eventually turned it on during the third period and got a goal from Bouwmeester.
Defenseman Carl Gunnarson played his first career NHL game for Toronto ... Leafs forward Phil Kessel and Flames forward David Moss are cousins ... Calgary has opened the scoring in 15 of its 18 games ... The Leafs warmed up in retro jerseys.