"We weren't playing as five-man units, we kind of got away from what we were doing," Langenbrunner said. "Tonight, there were a couple of real good stretches where we took control of the game."
Halak improved to 5-0-3 in his last eight starts with a 1.45 goals-against average and .945 save percentage. He is 8-7-5 this season, rebounding from a 1-6 start.
"I had a tough start and it affected my confidence," Halak said. "But I'm feeling better now. Tonight it was important to play well."
Halak stopped the final 26 shots he faced.
"He's moving around the net well and he's anticipating well," Hitchcock said. "He's played well ever since I got here."
Mike Smith made 27 saves for Phoenix after missing six games with a groin injury. Radim Vrbata scored his team-leading 19th goal late in the second period for the Coyotes.
Oshie scored a power-play goal when he pounced on the rebound of a shot from the point by Pietrangelo at 4:28 of the second period. His 13th goal made it 3-1, and the Blues improved to 8-0-3 in games in which Oshie scores.
Berglund added St. Louis' seventh empty-net goal of the season with 38 seconds left.
The win helped the Blues erase the memory of a three-game stretch in which they were outscored 8-3. They gave up 97 shots during the skid.
"It's January and this is the time when teams take it to the another level," Stewart said. "We did just that."
Stewart scored his eighth goal of the season from close range to give the Blues a 1-0 lead early in the first period. Langenbrunner made it 2-0 with his third of the season.
Vrbata brought Phoenix close, but Halak stopped all 10 shots he faced in the third period.
"After losing three straight, we had to come up big," Halak said.
The Coyotes, who will close a four-game road trip Thursday at Los Angeles, fell to 12-9-1 on the road.
Phoenix coach Dave Tippett wasn't pleased with his team's play.
"We need to put more will and commitment into the game," Tippett said. "They won a lot more of the one-on-one battles than we did.
"Our execution was slow and poor."
On the positive side, Smith said he felt comfortable in his return to the lineup.
"It's always nice to get back," Smith said. "It's not the outcome we were looking for. We got out-competed. We've got to find ways to win hockey games."
St. Louis, which beat Phoenix 3-2 on Dec. 23, has won five of seven against the Coyotes. The Blues won their first game of the new year after going 2-8-2 last January.
"We're starting to play with a lot more confidence," Stewart said. "It's beginning to show. We just have to keep working and doing the right things."
LW Alex Steen, who also has a Blues' best 13 goals, missed a third game because of concussion-like symptoms. ... The Blues are 17-1-1 when leading after the second period. ... Phoenix is 8-4-1 in its last 11 games in St. Louis. ... Phoenix had killed 20 straight power plays before Oshie's second-period goal. ... The Coyotes snapped a 1-for-14, power-play slump with Vrbata's goal. ... St. Louis is 17-0 when scoring at least three goals. ... Phoenix D Keith Yandle recorded a game-high six shots.