The Braves and Cardinals announced a significant trade Monday afternoon. The Braves acquired starting pitcher Shelby Miller and pitcher Tyrell Jenkins from St. Louis in exchange for outfielder Jason Heyward and reliever Jordan Walden.

"It was very difficult to trade Jason, but deal was made to help us short-term and long-term," Braves president of baseball operations John Hart said. "This deal also improves us in an area where we are woefully, woefully thin -- our minor-league system."

Heyward had been mentioned in trade rumors leading up to Monday's deal. He is in the final year of his contract after signing a two-year extension in Feb. 2014. The 25-year-old outfielder is coming off a disappointing 2014 season. He hit .271 with a .384 slugging percentage, .735 OPS, 11 home runs, 26 doubles and 58 RBI in 149 games.

The 24-year-old Miller is also coming off a disappointing campaign. The once highly touted pitching prospect went 10-9 with a 3.74 ERA and 1.27 WHIP in 32 appearances (31 starts). While he reached a career high in innings (183), Miller struggled with his command (3.6 BB/9) and saw his strikeout rate drop significantly (6.2 K/9).

"As we look at Shelby, we see that he has a chance to become a front-of-line rotation type of guy," Hart said.

Walden, the former Angels' All-Star closer in 2011, is under team control through 2016. He was 0-2 with a 2.88 ERA, 1.20 WHIP and three saves in 58 appearances for Atlanta last season.

Jenkins is a former top-100 prospect whose career has been slowed by a shoulder injury he sustained in 2013. He returned to action in 2014, going 6-5 with a 3.28 ERA and 1.31 WHIP in 13 starts at high Class A.