The Blues have been shut out in three of their past four games and are 19th in the NHL scoring 2.95 goals per game.
"We had to be better," Perron said. "We had meetings, I think it was three weeks ago, and obviously we knew something was going to happen if we didn't change. You can see one good game, then one game ... [at the Chicago Blackhawks], it kind of broke us (a 1-0 loss Nov. 14). I think we actually played a pretty good game and didn't score, almost like last night. It was hard and then we [are at the Vegas Golden Knights] and play probably our absolute best game of the season (a 4-1 win Nov. 16) and couldn't follow it up the next day (a 4-0 loss to the San Jose Sharks).
"It's obviously heartbreaking for [Yeo]. We feel for him. We let him down, and it's tough. We've got to find a way to move forward. He knows the business and that's what he signed up for, but it's never easy to take. He would want us to move forward and turn the page as soon as possible because he's been in this situation. We feel for him."
Craig Berube, 52, who joined St. Louis as associate on June 15, 2017, replaced Yeo. Berube was coach of Chicago in the American Hockey League in 2016-17 and coached the Philadelphia Flyers from 2013-15 (75-58-28).
Center Brayden Schenn played for Berube in Philadelphia and said some tough love might be what the Blues need.
"He's going to demand a lot," Schenn said. "Likes to play an up-tempo style of game, holds guys accountable. We need that in this locker room.
"I've had him before, guys had him in Chicago there. He likes a simple game, a hard game. He wants guys to compete to work, bring passion every night. At the end of the day, if you can do that, you're going to give yourself a good chance to win. Obviously, there's a system in place, but before that even all happens, you need to be able to come to the rink and put your best foot forward each night, and he's going to bring that out of most guys."
Berube's first game with St. Louis will be at the Nashville Predators on Wednesday (8 p.m. ET; FS-TN, FS-MW, NHL.TV).