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8/4/2013 12:40 A.M. ET

Miller takes away lesson from short outing

CINCINNATI -- Shelby Miller was cruising along on Friday night -- until he let off the gas pedal.

Miller tallied eight strikeouts and allowed only one harmless single through the first four innings against the Reds. Staked to a 12-0 lead in the fifth, he relaxed on the mound. Now he knows he shouldn't have.

"It was my own fault, just kind of letting off the gas pedal," Miller said. "Figuring I already had this game, I was going to go deep into the game. I already had it figured out and I stopped executing pitches."

Miller served up a three-run homer to Joey Votto in the sixth and ended up exiting the game before he could record an out in the frame. As a result, the Cardinals' bullpen had to cover the final four innings.

"I lost focus, I guess, something you shouldn't do as a starter," Miller said. "That could've gone completely different. The way it ended, it shouldn't have. You can look at my stats for [the game] -- it's nothing like how I performed."

For Miller, it proved to be a lesson learned. Such is life for a 22-year-old pitcher with only 22 big league starts under his belt.

"You're just constantly learning," said manager Mike Matheny. "We have to keep reminding ourselves how young a lot of these guys are and Shelby is absolutely one of those in that group."

Jay confident he's heading in right direction with bat

CINCINNATI -- Jon Jay has two hits in each of his last three games and is batting .358 over his last 17 contests.

So what triggered the flip of the switch for the center fielder, who entered his current surge with a .240 batting average?

"I don't know," Jay said, stumped by his peaks and valleys.

Jay has raised that mark to .258 and manager Mike Matheny felt confident enough in the 28-year-old's ability to place him in the leadoff spot Saturday for only the third time since June 1.

"Obviously, I didn't start off the way I wanted to," Jay said. "But I've felt good. That's just the way it goes sometimes. I don't know how to put a finger on it."

By the end of the season, Jay said, he expects to boast numbers that more accurately depict his hitting prowess. After all, he entered the 2013 campaign with a career .300 batting average in three Major League seasons.

"I was just having a down year, offensively," Jay said, "but I have confidence in myself that I'm going to finish off the year and look back on it and be proud of it."

Descalso recounts power display vs. Reds

CINCINNATI -- Daniel Descalso knew the question was bound to pop up, and he was prepared.

"Once, in the Minors," Descalso said, when asked numerous times Friday night and Saturday afternoon if he had ever before clubbed two home runs in one game.

Descalso socked two in Friday's 13-3 win over the Reds for his first career multi-homer game in the Majors. The power display boosted his total to five homers this season, a new career high.

"I'm not trying to do that," Descalso said, "but I'm trying to hit the ball hard and sometimes it goes over the fence."

Descalso led off both the fifth and seventh innings with solo shots. He turned on a fastball in the seventh and tucked it inside the right-field foul pole as the ball landed in the Cardinals' bullpen.

The 26-year-old has five hits in his last 11 at-bats, and since a brutal April, in which he batted .164, the infielder has hit .305.

"I feel like I've been swinging the bat well since May," Descalso said. "I've just been trying to stay consistent since then."

Matheny gives struggling Carpenter day off

CINCINNATI -- Matt Carpenter had strict orders to show up on time to the ballpark on Saturday.

"He had a stiff fine coming his way if he had gotten here any earlier," said Cardinals manager Mike Matheny.

Carpenter, known to arrive to the facility hours in advance of many of his teammates, is mired in a 1-for-29 funk that has dropped his average to .304 from .325 over the last week. Matheny met with the All-Star second baseman immediately following an 0-for-6 showing in Friday's win and told him to take a step back, take the day off on Saturday and take his mind off of baseball.

In addition to keeping Carpenter out of Saturday's lineup, Matheny told the 27-year-old not to man the infield during batting practice.

"It's a huge learning opportunity," Matheny said. "It's a huge chance for him to figure out what he has to do to bounce back from it. It's going to happen again if he stays in this game as long as I think he's going to. He's going to continue to have to figure out ways to right the ship and it usually comes from hard work and from knowing when to slow down and back off."

After replacing Pete Kozma in the sixth inning of Saturday's 8-3 loss to the Reds, Carpenter continued to struggle, going 0-for-2 with an RBI groundout. Carpenter has not tallied a hit in his last five games, his longest such streak this season.

"He's such a grinder," Matheny said. "The guy loves this game, loves this team and is just relentless in his work ethic. But right now, he just really needs to slow down and it'll all come back."

Worth noting

• With a day game Sunday, manager Mike Matheny opted to start Rob Johnson at catcher on Saturday night in lieu of Tony Cruz. It marks Johnson's first start since Aug. 12, 2012, when he was with the Mets.

Matheny said Johnson, who signed with St. Louis last November, was aware of the team's catching situation, with Yadier Molina established as an All-Star and Cruz settled into the backup role. That did not dissuade Johnson from finding a way to impart his knowledge onto the organization.

"He knew also that we had a lot of young arms on the way and he'd play a very important role for us," Matheny said. "It all kind of played out as we had discussed back in the winter. Now he's getting an opportunity to do something and help us out at the big league level."

• Matheny helped warm up his pitchers in the latter innings of Friday's victory. Matheny, a former catcher, cited a lack of bodies for the reason.

"This wasn't a glory day thing," Matheny said. "We were out of people. I don't want one of my pitchers out there warming somebody up. ... If we need an extra guy to catch, I like looking at what the pitchers are doing, so I enjoy getting back there."

One reporter noted that the Cardinals' shutout disappeared once Matheny started warming up the pitchers. The skipper snickered.

"Yeah, I did notice that," Matheny said.

• The Cardinals' wins the last two days over the Pirates and Reds marked the first time in franchise history that the club scored 13 runs in consecutive games against two different teams.

Zack Meisel is a reporter for MLB.com. Follow him on Twitter @zackmeisel. This story was not subject to the approval of Major League Baseball or its clubs.