Currently in his 10th NHL season, defenseman Jay Bouwmeester has never appeared in a postseason game.
Bouwmeester will face his former team for the first time since the deal as St. Louis seeks a season-best, five-game home winning streak Thursday night.
The Blues sought defensive depth as they clung to eighth place in the Western Conference when they sent a conditional first-round pick and two prospects to the Flames for Bouwmeester on April 1.
St. Louis (27-17-2) has won nine of 12 with Bouwmeester in the lineup and guaranteed the veteran his first postseason experience with a 3-1 win over Colorado on Tuesday.
"It's one little item checked off our list," captain David Backes said of clinching a playoff berth. "We've had a pretty good run to get to where we need to get."
The Blues, who conclude their regular season Saturday at home against NHL-best Chicago, are battling Los Angeles and San Jose for home-ice advantage in the first round.
Bouwmeester, who leads active players with 633 consecutive games played, spent six seasons with Florida before signing a five-year contract with Calgary in 2009, never making the postseason.
"You want to have success," said Bouwmeester, who recorded his fifth assist with the Blues on Patrik Berglund's power-play goal Tuesday. "It's fun winning. We've had a pretty good stretch here."
His former team, eliminated from the playoffs for a fourth straight year, also has excelled lately despite making multiple trades earlier this month.
Calgary (19-23-4) had won five of six and three straight before falling to Nashville 4-3 on Tuesday. Rookie Roman Cervenka scored twice to give him three goals and an assist during a season-best, three-game point streak.
The Flames have been playing with plenty of new faces with eyes on the future after trading Bouwmeester as well as franchise cornerstone Jarome Iginla to Pittsburgh and Blake Comeau to Columbus.
"There's a lot of new guys playing," said 36-year-old goaltender Miikka Kiprusoff, who reportedly is considering retirement after the season. "You know, it's not fun to lose but it's good to see our young guys. They played well again (Tuesday) and good to see them getting chances to play."
Kiprusoff has a career-worst 3.44 goals-against average this season, but he made 36 saves and Cervenka scored twice as the Flames beat St. Louis 3-2 in the last meeting March 24 to end a three-game skid in the series.
St. Louis has held opponents to one goal in four consecutive home games - all victories. Brian Elliott started each of those contests after going 1-4-1 with a 4.31 GAA in his first six home outings.
Elliott is 7-2-0 with a 1.14 GAA in his last nine starts overall and has a 1.83 GAA in five career starts versus the Flames.
Kiprusoff is 7-3-1 with a 1.36 GAA in his last 11 versus St. Louis, which may be without defenseman Barret Jackman after he was injured blocking a shot Tuesday.