The loss Friday ended St. Louis' four-game winning streak and six-game point streak (5-0-1).
The Blues were last in the NHL at 15-18-4 on Jan. 2. They are 26-10-4 since, including an 11-game winning streak from Jan. 23-Feb. 19.
"I think it started in December on the West Coast," Perron said.
The Blues went 2-1 on a three-game trip from Dec. 18-22, when they defeated the Edmonton Oilers 4-1 and the Calgary Flames 3-1, and lost to the Vancouver Canucks 5-1.
"The feeling of our club was starting to turn, we were outshooting clubs every night, not always getting results, but you could feel we were carrying the play most nights," Perron said. "Obviously we went on an 11-game winning streak, so that was huge."
Vladimir Tarasenko and Perron scored, and Jordan Binnington made 21 saves for the Blues.
Tarasenko scored from the goal line to the left of the net for his 30th of the season at 14:35 of the first period, giving the Blues a 1-0 lead. Perron made it 2-0 27 seconds later, scoring on a wide-open tap-in from the slot off a pass from Jaden Schwartz.
"Scoring first, getting the momentum, feeling confident and we just kind of let that guard down," St. Louis center Ryan O'Reilly said. "We thought they'd kind of go away, but they're just a team that keeps skating, waiting for bounces and jumping in the rush every time. We just gave them too much."