The 30-year-old goalie took the blame for his gaffe.
"I misread the speed of the puck or maybe I overestimated my skating ability," Fasth said. "But we all know it was a bad decision by me.
"Those things happen, and unfortunately it happened tonight in a tight game and ended up being the game-winning goal."
MacDermid opened the scoring at 9:03 with a short backhander after Antoine Roussel found him cruising down the slot. The lead lasted just 18 seconds as Cogliano converted a centering pass from behind the net by David Steckel after the puck took a strange bounce off the end boards on a dump-in by Bryan Allen.
"We didn't help ourselves, but that was (Dallas') best effort," Boudreau said. "We knew if they scored the first goal and had a lead coming out of the first period, they were going to be very tough. It seemed like after we tied it up, for about 10 minutes we fell apart and started watching them pass the puck.
"Once they got the 3-1 lead, they played pretty solid the second and third periods."
MacDermid sustained an upper body injury on his first shift of the second period and didn't return.
The Stars and Ducks played their final game as division rivals, due to the realignment of the NHL in 2013-14.
NOTES: MacDermid's first NHL goal on Wednesday came on the 31st anniversary of his father Paul's first NHL goal. They are the second father-son duo to score their first goals on the same date. The other was John "Peanuts" O'Flaherty and son Gerry, who accomplished the feat on Nov. 3 in 1940 and 1972. ... With Jonas Hiller sitting out the game because of illness, the Ducks shifted their backup goalie. Jeff Deslauriers was at the end of the bench for the first 3:57, and Igor Bobkov replaced him. ... The Ducks are Lombardi's fifth team in five seasons. He had about 12 1-2 minutes of ice time, had only one shot, and was a minus-1. ... The Ducks, who came in with the league's third-best power play, were 0 for 4. ... The Ducks outshot the Stars 28-25. Dallas hasn't outshot an opponent in nine games.