Coach Mike Yeo was fired on Nov. 20, replaced by Craig Berube. St. Louis has gone 12-8-1 in its past 21 games to get back in the Central Division and Western Conference races.
There are three points separating seven teams in the Western wild-card race: the Dallas Stars, Avalanche and Vancouver Canucks each have 52 points, the Anaheim Ducks have 51, the Arizona Coyotes 50 and the Blues and Edmonton Oilers each have 49.
"It's a tough league to win in and there is so much parity," O'Reilly said. "From the first-place team to the last-place team, there is not a lot of difference. Each night, anyone can beat anyone and I think from a fan's perspective, that is a great thing to see. When you get to the playoffs, you have a chance to win.
"Seeing teams go through skids or rough runs, it just shows that it is a momentum league and a competitive league."
The Blues look to have the momentum that eluded them well into December, and are becoming the dangerous team many predicted they would be at the beginning of the season.
O'Reilly is a convert.
"When we play together, when we are playing for each other, you can see we are a good team." O'Reilly said. "When the forwards invest in the D and the D invest in the forwards and we play quick and we work together, we are confident out there. It is one of those things that is going to get us in the playoffs and I am confident that we will."