"Basically, we gave it to them," Canadiens center Phillip Danault said. "We were flat-footed. We didn't use our speed, our strength and they capitalized more than we did.
"I don't think it's acceptable for our team because we're battling for a playoff spot, but we're going to look at it and it's tough to swallow that one."
Two of Binnington's biggest saves came off a 2-on-1 against Victor Mete with 16:17 remaining in the third period and another on Jonathan Drouin, who entered the Blues zone with speed and split the defensemen with 6:06 remaining.
"I got a piece of it and I felt it pop up," Binnington said of the save against Mete. "You kind of just hope for the best and hope the D-man was there to kind of block the goal line too. It was a fortunate play.
"I think I liked that Drouin save where he kind of came in past the D-man. I liked that one."
Thomas gave the Blues a 1-0 lead on a power-play goal 1:56 into the first, but left the game midway through the period because of an upper-body injury.
"I'll find out more tomorrow when he gets evaluated by doctors and stuff like that," Blues coach Craig Berube said of Thomas. "He's been really good for a while now. It's unfortunate. We hope that it's not too bad and he's OK."
Sundqvist's shorthanded goal at 16:24 of the first made it 2-0. It was the Blues' third shorthanded goal of the season.
"I don't know how I got the puck, but Carl [Gunnarsson] kind of swung it and it just ended up in my skates," Sundqvist said. "I saw right away that we were going to have a 2-on-1. Obviously, O'Reilly's a way better passer than me, so I was just trying to give it to him as quick as possible.
"I didn't think a lot. That was the first thing that came to my mind."
Bouwmeester's breakaway goal made it 3-0 at 6:04 of the second period.
Gallagher made it 3-1 with a power-play goal at 9:02 of the second to end Binnington's shutout streak at 105:24, a shot that caromed off Alex Pietrangelo's skate.
Blais scored his first of the season and second NHL goal at 9:19 of the third for the 4-1 final.