Braves president John Hart will take over GM duties while the team searches for a new one.
In a statement Monday, the Braves said, “the resignation comes as a result of a breach of Major League Baseball rules regarding the international player market.” Hart said the Braves will give MLB their full cooperation during the probe.
An MLB spokesman would not provide details on an ongoing investigation.
The Braves, who finished 72-90 this year, have been very active in the international market in recent years.
Coppolella was promoted to GM after the 2015 season.