Now, he's on their side.
The former Avalanche forward made a two-goal debut, helping energize a franchise coming off a pair of high-profile trades, in a 9-3 rout of the Anaheim Ducks on Saturday night. He was running on adrenaline, after learning he'd been traded about 11 p.m. Friday night and taking two flights to St. Louis.
"It was a perfect start," Stewart said. "By the time I landed, I had three or four text messages from the boys and it was very comforting. It was an easy adjustment."
The 23-year-old Stewart totaled two goals in his last 14 games with Colorado after returning from a broken hand. Against the Blues, he has eight goals and 15 points in only nine career games.
"Yeah, a couple of the boys let me know before the game," Stewart said. "They were calling me the Blues killer, so I found that kind of funny."
The Blues just missed a franchise record with two goals in a 7-second span of the first period. T.J. Oshie had his first career two-goal game with an assist, playing a hand in both goals of the quick flurry that erased a two-goal deficit.
The record is two goals in 6 seconds, also against the Ducks on Oct. 11, 2010, at home.
It sparked a season best for scoring, topping the previous best by three goals. The Blues are 13th in the Western Conference, five points out of the final playoff spot, and in the last two days shook up the roster by trading Erik Johnson, Eric Brewer and Jay McClement.
"We lost three teammates, great guys, and it was a bit of a shock," said forward Andy McDonald, who had two goals and an assist. "It wasn't like we had a few days to adjust, it was on a game day, and I think the guys handled it pretty well."
Stewart was the fifth player in franchise history to score twice in his debut, getting his 14th and 15th on power plays in the second period after totaling two goals in his last 14 games with Colorado. Kevin Shattenkirk, also acquired from the Avalanche in the deal for Johnson, the No. 1 overall pick in 2006, set up Stewart's second goal.
St. Louis was 3 for 5 on the power play and Alexander Steen had a short-handed goal to wrap up the scoring plus two assists.
The Ducks have been vulnerable with Jonas Hiller sidelined the last three games by a recurrence of dizziness and fatigue, surrendering 21 goals. Backup Curtis McElhinney was yanked after giving up four goals on 11 shots in the first period in favor of rookie Timo Pielmeier.
"It doesn't matter who's in net," forward Ryan Getzlaf said. "It's not that they're bad goals. They're getting bounces against us because we're not working for them."
Ty Conklin had a shutout Friday at Buffalo after the Blues traded Brewer, who had been captain, to Tampa Bay. He was lifted at 16:42 of the first period after surrendering three goals on five shots with Ben Bishop finishing.
Teemu Selanne scored his 19th for Anaheim before getting a game misconduct penalty for unsportsmanlike conduct in the second period. Jarkko Ruutu and Getzlaf also scored for the Ducks, who'll play their next seven at home.
"It doesn't matter if you're at home or on the road," Getzlaf said. "We're going to have to go back to work."
The Blues set a season best with four goals in the first period, then matched it in the second in their highest scoring game since Brendan Shanahan had three goals and two assists in an 11-1 victory at Ottawa on Feb. 26, 1994. McDonald had two goals, scoring on the front end of the 7-second salvo off Oshie's setup.
Alex Pietrangelo had three assists for the Blues. ... In the last seven meetings, there's been a single one-goal game. ... McDonald has eight goals and four assists in his last seven games against his former team. ... The Ducks had won six of their previous seven on the road. ... Fans cheered a reference to the Brewer trade during a pregame feature on the videoboard.