ATLANTA -- Jason Heyward stirred up enormous expectations when he joined the Atlanta Braves at age 20. He homered in his first big league at-bat. He was voted to the All-Star Game as a rookie. He was hailed as the future of the game by Hank Aaron.

Heyward never quite lived up to the hype, and now he's heading to a team looking to bounce back from tragedy.

Concerned that Heyward would leave as a free agent after next season and rebuilding with an eye toward their new stadium, the Braves dealt their right fielder and reliever Jordan Walden to the St. Louis Cardinals on Monday for promising pitcher Shelby Miller and a minor-leaguer.

"It's very difficult to trade Jason Heyward," said John Hart, the Braves' new general manager. "But the deal was made to help us not only in the short term but the long term."

The NL Central champion Cardinals felt compelled to pursue Heyward after top prospect Oscar Taveras was killed in a car crash last month in the Dominican Republic. The team hopes to sign Heyward to a long-term extension but didn't want to go into next season without adding to the offense.

St. Louis Cardinals starting pitcher Shelby Miller throws a pitch during the first inning of Game 4 of baseball s NL Division Series against the Los Angeles Dodgers, Tuesday, Oct. 7, 2014, in St. Louis. (AP Photo/Charles Rex Arbogast)

"The reality is we have to move on," St. Louis general manager John Mozeliak said.

Heyward said he was not surprised by the trade, especially since there were never any serious talks on a new deal with the Braves. He is due to make $7.8 million in the final season of a two-year contract.

"This is a business," said the 25-year-old Heyward, who grew up in the Atlanta area and was one of the team's most popular players. "I was definitely open to long term, but that conversation never took place."

The deal signals a long-term strategy for rebuilding the roster by the time the Braves move into their new suburban ballpark in 2017.

By trading Heyward and Walden, the team shed what could have been as much as $10 million from next season's payroll while acquiring a 24-year-old pitcher who is not yet eligible for arbitration and can't become a free agent until after the 2018 season.

"We want to build something that's going to sustain," Hart said.

After his promising rookie year, Heyward was plagued by injuries and struggled to put up the sort of power numbers the Braves expected. He's had only one season with at least 20 homers and 80 RBIs; this past year, he batted .271 with 11 homers, 58 RBIs and 20 stolen bases, though he did win his second Gold Glove.

Heyward frequently batted leadoff for the Braves, which the Cardinals believe hurt his power production.

After the Braves slumped to their first losing season since 2008, general manager Frank Wren was fired. Hart took over and is looking to build depth throughout the organization, with a focus on starting pitching.

Atlanta is hampered by bad contracts, which will limit Hart's flexibility in the short term.An anemic offense was the biggest problem as the team collapsed down the stretch, but Hart didn't sound overly optimistic about addressing those needs.

"Some guys are going to have to have better years," he said. "You can't go out and replace your entire club."

Ervin Santana and Aaron Harang, who combined for 26 wins last season, were on one-year deals with the Braves and unlikely to return. With that in mind, Hart was looking to land at least two starting pitchers this offseason.

He's halfway there.

Miller went 10-9 with a 3.74 for the Cardinals, after going 15-9 with a 3.06 ERA as a rookie in 2013. He joins a rotation that also includes young starters Julio Teheran, Alex Wood and Mike Minor.

Walden made $1.49 million this past season and could have earned a raise in arbitration. He was 0-2 with a 2.88 ERA and three saves as a set-up reliever for closer Craig Kimbrel.

Atlanta also acquired right-hander Tyrell Jenkins, who pitched for Class A Palm Beach this past season.

"The Braves have always been a pitching organization," Hart said. "We have the makings of a quality young rotation."

St. Louis felt it had the pitching depth to deal Miller. Youngsters Carlos Martinez and Marco Gonzales will get a chance to fill the rotation spot.