"I'm going to trust it all year," Pineiro said. "It's going to be the pitch I go to every time."
The Cardinals backed him with a robust offense that beat up on John Maine, scoring five or more runs for the seventh straight game.
"If it's September and we're getting 5-6 runs a game, then it would be a good time to talk about it," manager Tony La Russa said. "But we're taking hungry at-bats."
Joe Thurston and Skip Schumaker had an RBI apiece for the Cardinals, who will go for a three-game sweep Thursday with Kyle Lohse opposing Livan Hernandez. St. Louis has won nine of 12 since a 1-2 start, including six in a row at home.
Maine (0-2) matched his career worst with five walks while attempting to fine-tune his delivery. He left trailing 5-1 with the bases loaded and two outs in the sixth. The right-hander has a 7.47 ERA and nine walks in 15 2/3 innings.
"I know I'm a better pitcher than this," Maine said. "I'm working hard between starts and I'm just not getting the results right now.
"A lot of times I'm making the pitches I want to make, I'm just a hair off."
The Mets have lost three in a row while getting outscored 15-8.
"Our starting pitching has to be something we can depend on and count on," manager Jerry Manuel said. "Right now, other than Johan [Santana], for the most part it's been a struggle."
Daniel Murphy had an RBI single in the third and Beltran hit an RBI double off Dennys Reyes in the ninth for his third hit. Ryan Franklin earned his fourth save in four chances by getting pinch-hitter Gary Sheffield to pop up for the final out.
Pineiro (3-0) retired 13 straight hitters on 35 pitches beginning with the final out of the fourth, all but three of them on ground balls. He was pulled after Wright's leadoff double in the ninth.
Pineiro pitched to contact, walking two for the first 3-0 April start of his career while improving to 8-2 with a 3.61 ERA in 16 career games at Busch Stadium.
"I'm going to keep riding that as long as I can," he said. "That's going to be my game plan no matter if I'm at Wrigley Field, Coors Field, whatever field I am."
A lifetime .082 hitter, he also singled in the seventh and drew a leadoff walk and scored in the third.
The St. Louis defense contributed a couple of nice plays, with Thurston making a diving stab at third with two on and two outs in the fourth to rob Luis Castillo, and shortstop Khalil Greene going deep into the hole to throw out Ramon Castro in the seventh. Left fielder Chris Duncan reached into the stands to snare Murphy's foul fly in the first.
Pujols, who entered the game tied for the NL RBI lead with 16 along with teammate Ryan Ludwick, had a sacrifice fly in the first and a run-scoring single in the third. He is 5-for-11 with two homers and 11 RBIs against Maine.
Maine was in trouble every inning except the fifth, when he retired the 3-4-5 hitters on eight pitches after Pineiro had an eight-pitch top half. Duncan followed Pujols' RBI single in the third with a run-scoring groundout for a 3-0 lead, and Thurston had an RBI triple and scored on Schumaker's single in the fourth to make it 5-1.
Questions have been raised about the limited views of the playing field from the visitors' bullpen at Citi Field, the Mets' new ballpark. The commissioner's office is working on it with the Mets, baseball spokesman Pat Courtney said. ... Ludwick, among the league leaders with a .370 average and tied for the lead in homers (five) and RBIs (16), was the odd man out in the four-man outfield rotation. He popped up as a pinch hitter with the bases loaded against Casey Fossum to end the sixth, but La Russa said Ludwick would start the next four games. ... According to the Elias Sports Bureau, the Mets' 6-4 loss Tuesday was their first under Manuel in which they led by at least four runs. ... Greene walked his first three times up, giving him five straight over two games, before flying out in the sixth. ... Jose Reyes is 7-for-12 against Pineiro after going 1-for-3 with a single to start the game. ... Duncan was 0-for-4, ending a 13-game hitting streak to start the season.