Washington entered the day needing a win or an Atlanta loss to clinch the National League East title. The Nats will have to wait at least one more day to pop any champagne bottles. The Cardinals, too, positioned themselves for a possible Monday clinch.
With the victory, they hold a two-game lead over the Dodgers in the Wild Card race, after Los Angeles beat the Rockies later on Sunday.
"This is not about one day," said Beltran. "This is about going out there and being able to win ballgames. This is not about me. This is about the team. We're in a position where we have an opportunity to win the Wild Card and compete for a spot in the playoffs."
The Cardinals broke out for a five-run second inning, capped by Beltran's 31st homer. Two innings later, he delivered another two-run blast. Both homers came on 1-2 counts but were hit from different sides of the plate. It was the ninth time the switch-hitter has homered from both sides in a game.
Though Beltran leads the Cardinals in home runs this season, long balls have been rare for him as of late. From Aug. 11-Sept. 29 -- a span of 141 at-bats -- Beltran went deep twice. He had driven in just seven runs all month. He drove home his fifth run on Sunday with an eighth-inning single.
"As ballplayers, you're going to go through good stretches and bad stretches," Beltran said. "I try not to focus on that. I try to focus on the work that I do to prepare myself. I approach the game every single day with the mentality to do good for the team. Some days it happens. Some days it doesn't happen."
There has been some sustained traction, too, by the right fielder. Since Sept. 13, Beltran is 17-for-48.
If Beltran can maintain the spark, the dividends could be significant should the Cardinals advance to the postseason.
"He's been working so hard," Matheny said of his two-hole hitter. "The guy cares so much and it just sometimes isn't translated by how he just goes about it in such a workman-like attitude. It has really been bothering him that he hasn't been able to step up and contribute lately."
Beltran wasn't the offense's only contributor on Sunday. The Cardinals finished off the three-game series with a run output of 26, 12 more runs than the club scored a month ago during a four-game series in Washington. The Nats entered the weekend leading all NL rotations in ERA.
On Sunday, St. Louis jumped on starter and St. Louis-area native Ross Detwiler early.
A pair of walks and potential double-play ball that Nationals second baseman Danny Espinosa muffed into an error loaded the bases with no outs in the second. Surprising September contributor Pete Kozma then drove two home with a double.
With two out in the inning, Kozma scored on Jon Jay's single to left. Beltran followed with the first of his two home runs.
Detwiler said afterward that he never found a consistent arm slot in his first career appearance at Busch Stadium.
"They're paid to hit, and we're paid to pitch," Detwiler said. "They got the best of me today, and hopefully we see them and I can go out there and throw against them and show them what I have next time."
Before Beltran would go deep for a second time, the Cardinals tacked on two insurance runs with the assistance of a pair of wild pitches from Chien-Ming Wang. Kozma had a sacrifice fly during that two-run third inning, giving him his fourth multi-RBI game in his last seven starts.
Kozma has driven in at least one run in seven of the team's last eight games and tallied a hit in each of his other three plate appearances on Sunday.
"We needed someone to step up," Matheny said. "Who would have thought it would be Pete Kozma?"
"I've had a hot streak before," added Kozma, who hit .232 in 131 Triple-A games this season. "People didn't see it because I was in the Minor Leagues."
Washington cut into the Cardinals' lead with a four-run fourth off starter Lance Lynn, who served up homers to Bryce Harper and Espinosa. But Lynn evaded additional damage and eventually finished 5 1/3 innings. That qualified him to earn the win, his 18th of the year.
Lynn is one of just four NL pitchers to reach the 18-win mark this year. He did it in 34 games (29 starts) and is 4-0 since being moved back into the rotation.
"It doesn't mean anything if we don't make the playoffs," Lynn said when asked about No. 18. "I have a great team behind me. I was put into a great situation."
Indeed, Lynn did benefit from tremendous run support all season. The Cardinals averaged nearly six runs in Lynn's starts this season. St. Louis won 21 of the 29 games Lynn started.