ST. LOUIS — Lance Lynn no longer has the element of surprise on his side.

The St. Louis Cardinals' right-hander lost to the San Francisco Giants 4-2 on Tuesday night, then made the point that other teams have made adjustments to his style.

"I've just got to keep working, keep trying to get better," Lynn said. "That's part of the game. They're starting to learn what I do. I've got to keep trying to get better and keep improving."

Lynn made a mistake on a slider that was hit for a three-run homer by Buster Posey in the first inning that put the Giants on top. The inning began with singles by Angel Pagan and Marco Scutaro.

Allen Craig hit two home runs for the Cardinals, but they weren't enough to overcome Posey's 18th homer of the season.

"One swing, one pitch cost me the game," said Lynn, who is 13-5 with a 3.52 ERA in 22 starts. "It was supposed to be off (the plate). It just spun. I wasn't trying to give him anything to hit there. It was just a bad pitch.

"Maybe if I make a good pitch there, he rolls over it to short and it's a different ballgame. ... I'm making the bad pitch at the wrong time, and it's costing me a lot of runs when I do it. I've got to keep that ball in the ballpark and it's a whole different ballgame."

Lynn allowed the leadoff hitter to reach in four of his six innings. Twice, the Giants made him pay, including the sixth when Brandon Belt singled, stole second and scored on Joaquin Arias' double.

"That's been kind of the thing that's been my Achilles' heel the last couple of starts," Lynn said. "I can't get that first hitter out and it's a battle the rest of the inning. When you're pitching with runners on base, you've got to make pitches."

Cardinals manager Mike Matheny agreed that teams have adjusted to Lynn's style and repertoire.

"I think you're seeing a young pitcher and the league is getting more looks at him," Matheny said. "He's still giving us a chance; we had a chance to win today. He's been doing that pretty consistently for us."

Schumaker faces lefty

Second baseman Skip Schumaker, who often has been benched against left-handed pitchers, was in the lineup and batted leadoff Tuesday against Barry Zito.

Schumaker had been 7-for-12 (.583) with three doubles and four RBIs in his career against Zito. However, he was 0-for-4 with a strikeout.

"He's had pretty good success with a limited number of opportunities he's had," Matheny said before the game. "We've got to keep Skip sharp. We know that he can be a real spark to this offense. He's done a nice job for us defensively, too.

"All in all, we've got to figure out ways to keep everybody going. But being 7-for-12 with three doubles is not too bad. ... When you have some lopsided numbers, one way or the other, you have to pay attention to them."

Daniel Descalso has been playing well on offense and defense in recent weeks, seizing consistent playing time.

But as has been the case all season, second base will be a ride-the-hot-hand position for Matheny and the Cardinals.

Next season, Kolten Wong figures to receive every opportunity to make the team in spring training. Wong, the Cardinals' first-round draft pick last year, began Tuesday hitting .283 with 17 doubles, eight home runs and 43 RBIs in 102 games at Class AA Springfield.

Beltran reels 'em in

Right fielder Carlos Beltran registered his team-leading sixth outfield assist Monday when he nailed Brandon Belt at second as Belt tried to stretch a single.

Matheny said Beltran plays with such grace that he often gives the impression that he isn't going full-bore.

"He baits them in," Matheny said of runners who gamble against Beltran's strong and accurate arm. "Those guys (in San Francisco) should remember how good his arm is.

"He's a little bit deceptive. Fortunately, the throws have been right on the mark or else (the runners) would be safe. It's not like he's throwing them out by a long ways. They're all bang-bang. He knows how to pace it."

Matheny said Beltran gives what his body has.

"I don't think he's trying to con anybody," Matheny said. "There are some days his body's not just able to go at the speed that maybe you would like to think he could go. He's going after balls sometimes a lot harder than what it looks. We just need to get the rest of his body to cooperate some days."

Beltran made a nice catch in the fifth inning Tuesday, gliding to the wall before leaping to take extra bases away from Hunter Pence.

Beltran was in on another crowd-pleasing play in the seventh.

Melky Cabrera lined a hit into the right-field corner. Beltran got to the ball and fired a strike to second baseman Schumaker, whose relay to third baseman David Freese was perfect. Freese applied the tag to the sliding Cabrera.

Contact reporter David Wilhelm at dwilhelm@bnd.com or 239-2665. Follow him on Twitter: @DavidMWilhelm.