The Cardinals have -- and will -- preach confidence in the numbers surrounding Matt Carpenter, knowing some of his advanced and predictive marks rank among the best in baseball. But they also acknowledge one important component in particular.

“You can only build a line of reasoning for so long,” president of baseball operations John Mozeliak told reporters prior to Friday’s series opener against the Reds. “At some point in this game, you're truly measured on what you do.

“There's that old saying, that, ‘If ain't broke don't fix it,’ but if something isn't working, maybe you need to try to make some adjustments. I do appreciate the fact that he is making hard contact, I do appreciate the fact that he's trying to remain positive in this. But on some level, you've got to see production out of that. Hopefully his fortunes change, because he certainly would help our lineup and help our team. But at some point, it's gonna be hard to just do the same thing over and over again.”

Carpenter, 35, is hitting .081 (3-for-37) through 10 starts, including seven starts over the team’s last nine games -- a span over which he’s collected all three hits of the young 2021 season: a bunt single, a homer off the foul pole and a single into right-center on which he was thrown out trying to stretch it into a double.

The fact that Carpenter has had those brief glimpses give credence in the advanced numbers. But what doesn’t get picked up in hard-hit and barrel rates are strikeouts. Carpenter has 16 of those over 37 at-bats this season, including seven over his last 11 at-bats.

“I'm not walking in his shoes. … [But] I'm not sure even if making adjustments changes his production all that much, because he's so wedded to one version of his swing,” Mozeliak said. “I think the complexities of this are maybe a lot more difficult than maybe all of us realize. If it was as simple as a light switch, I'd recommend flipping it.”

The Cardinals face a crossroads with Carpenter, who makes $18.5 million this year and has a vesting option based on plate appearances for 2022 that he’s not in line to hit. As some players start to return from injury -- as was the case of Tyler O’Neill on Friday -- the starting opportunities and at-bats will become more scarce for Carpenter.

When that becomes the case, Carpenter’s role will become more muddied. The Cardinals would love to get him going, but they also don’t want to sacrifice the production of his productionless at-bats to do so. Mozeliak said the next 7-14 days will be telling for Carpenter's outlook.

Part of that equation will be needing to see a change from Carpenter -- both in the batter’s box and in the box score.

“I think I would do something different,” Mozeliak said. ”Isn't that the definition of insanity -- do the same thing over and over again and expect a different outcome?”

O’Neill back but still down
The aforementioned O’Neill (right groin strain) was activated off the injured list prior to Friday’s opener against the Reds but was kept out of the starting lineup due to a sore foot, sustained after fouling a ball off of it in a simulated game on Thursday. Manager Mike Shildt said he believed it was O'Neill's left foot.

O’Neill will start when fully healthy, hoping to right a tough start to his season with 14 strikeouts in his first 28 at-bats.

To make room for his return, the Cardinals placed John Nogowski on the IL with a bone bruise on his left hand, retroactive to April 20.

Nogowski was hit in the hand by a pitch on April 7 in Miami, but played through the ailment. The Cardinals expect him ready to return as soon as -- or near after -- he’s eligible to be lifted off the IL.

Worth noting
• The Cardinals lineup hit its biggest shakeup of the season in Friday’s series opener, with hot-hitting Dylan Carlson batting second and Paul Goldschmidt and Nolan Arenado shifting to Nos. 3 and 4, respectively. All are batting in those spots for the first time of the season.

• Mozeliak said that around 60 percent of Cardinals Minor League players had received their vaccines by Friday, with more expected to join that group in the coming week. The federal government’s pause on the Johnson & Johnson vaccine distribution has slowed that process.

• A return by the end of May for Miles Mikolas (right shoulder discomfort) is a “fair bet” for Mozeliak, adding that the right-hander likely has a pair of simulated games on his docket before making a rehab outing in a Minor League game.

• As for Harrison Bader (right forearm strain), Mozeliak said he’d take the under regarding May 15 as a potential return date for the center fielder, who recently started to face live pitching and is throwing from 120 feet.