"Good for him," Braves interim manager Brian Snitker said of Cervenka. "I mean from where he was a year ago to now, that's great."
Cervenka was drafted in the 27th round in 2008 by the Red Sox before he was sent to the Cubs in the Marlon Byrd trade in '12. Chicago released him in May 2015, and the Braves signed him as a free agent in July of that year.
Cervenka hasn't given up a run in his past three appearances, but he allowed four to cross the plate on July 30 against the Phillies on 21 pitches in one-third of an inning.
"[Cervenka] had the one bump the other night, but other than that, since I've been here, he's been really good," Snitker said. "Somebody you could depend on and someone who you could do that little matchup thing for an inning in a game."
Seymour, a 21-year-old speedster who was a seventh-round Draft pick in 2014, had been ranked the Marlins' No. 8 prospect by MLBPipeline.com. He played 103 games at Class A Greensboro this season, batting .252 with 36 stolen bases.
Mader, 22 years old and drafted in the third round in '14, was Miami's No. 24 prospect. Mader pitched in 22 games for Class A Advanced Jupiter, starting 21, and went 7-6 with a 3.50 ERA and 81 strikeouts in 103 innings.
David Adler is a reporter for MLB.com based in New York. Follow him on Twitter at @_dadler. Nick Krueger, an MLB.com reporter based in St. Louis, contributed to this story. This story was not subject to the approval of Major League Baseball or its clubs.