Stephenson, who was recalled from Triple-A Louisville to make his first start of 2017, gave up five earned runs and eight hits over 5 1/3 innings with two walks and five strikeouts.
Marlins lefty Chris O'Grady labored with six walks over 4 2/3 innings in a no-decision. O'Grady allowed three earned runs on four hits with six strikeouts. He permitted a Billy Hamilton leadoff infield hit, followed by three-straight walks -- including one to Adam Duvall that forced home a run in the first inning for a 2-1 Cincinnati lead.
Leading off the fifth, Patrick Kivlehan clobbered O'Grady's 2-1 changeup for a game-tying homer.