CINCINNATI -- When Tommy Edman was called up over a month ago, no one really knew what he could do. For a while, it seemed like all the rookie could do was hit.

Then the Major Leaguers facing him adjusted. Edman’s hot start slowed after the All-Star break. He knew it was bound to happen sometime. So he adjusted, too.

The adaptations Edman made to big league pitching culminated to his first career grand slam Thursday night in the Cardinals’ 7-4 series opening win over the Reds at Great American Ball Park.

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His first-pitch, 408-foot blast was the Cardinals’ first grand slam of the season and broke the 3-3 tie in the top of the sixth inning.

In his 21 games before the All-Star break, Edman hit .283 with more than a few timely hits, including his first home run, a game-tying shot in the eighth inning against Miami on June 20, and earned his playing time.

Over the five games after the All-Star break, Edman was hitting .154 (2-for-13). He began the adjustments against the Pirates on Wednesday with two singles, when he focused on recognizing when pitchers will try to make him chase. He pointed to his single in the seventh, when Francisco Liriano threw Edman a changeup that Edman had chased the day before. He took the ball, which set him in a favorable count for the hit.

The grand slam Thursday was further evidence that he is on the right track.

“This is an adjustment league with everything that’s out there with video, scout reports, metrics,” Cardinals manager Mike Shildt said. “People are going to make adjustments when you have success. It’s a fine line because you want to stay with your success, but you want to be aware of how you’re approached. Tommy is a very smart guy, conscientious guy, even-keeled guy. That’s a beautiful way of making something difficult, simple.”

But Edman wasn’t the only Cardinals player to break out Thursday night thanks to the small adjustments he made.

It had been over a month since Paul DeJong hit a home run until his two-run shot off the left-field foul pole in the fifth inning. It brought the Cardinals within one of the Reds, after Dakota Hudson allowed three runs over his five innings of work. It was also DeJong who tied the game with a single in the sixth before Edman’s slam.

When he last homered -- June 16 against the Mets -- DeJong wasn’t even an All-Star.

“It’s a good release,” DeJong said. “I felt like this month really flew by, it didn’t really feel like a month. That’s when you know I wasn’t slowing the game down and wasn’t really present to let that many at-bats go by.”

Between June 16 and Thursday, DeJong played in 23 games. He hit .165 in those games with 20 strikeouts. His on-base percentage was .224, and he had just three RBIs.

DeJong said he adjusted his mindset to better trust his abilities. He knows he can be an impact player as the Cardinals battle through the division. In the games out of the break, he fought the urge to swing at everything. Instead, he stepped into the box and saw the ball without imagining what the pitch was before it left the pitcher’s hand.

“Today, I felt quiet and calm in [the box],” DeJong said. “It showed. Turned over a new leaf and going to continue to impact the game every day.”

Ultimately, impacting the game is what DeJong, who has started 91 of the Cardinals’ 95 games, will need to do. The same goes for Edman, as he fights for playing time with Matt Carpenter on the injured list.

The Cardinals are tied with Milwaukee for second in the National League Central, 2 1/2 games behind the Cubs. DeJong said the Cardinals know the division is up for grabs. He also knows the Cardinals are hungry to grab it.

“I’m in the perfect position to keep helping our team to win every day,” DeJong said. “Finishing strong to me is the biggest thing I want to do as an individual and our team.”