Whether Steckenrider's stint is a few days or longer, the righty is one of the organization's more interesting pitching prospects. The 26-year-old throws a 98-plus mph fastball, and he has impressed at New Orleans, posting a 1.25 ERA with 26 strikeouts in 21 2/3 innings.
"He's a power guy, and he's been pitching well," Marlins manager Don Mattingly said on Tuesday. "They've used him in a couple of different roles. He's been throwing multiple innings down there, and he's also been throwing one-innning stints."
Steckenrider is ranked by MLBPipeline.com as Miami's No. 9 prospect. The Marlins selected Steckenrider out of the University of Tennessee in the eighth round in the 2012 Draft.
In Steckenrider's last 10 games, the 6-foot-5, 215-pounder has a 0.77 ERA with 14 strikeouts in 11 2/3 innings.
In Spring Training, Steckenrider got a taste of being in big league camp, and the focus, when he was optioned to New Orleans, was to command his pitches.
"I just had to get my feet under me, and get all my pitches going back into the season," Steckenrider said. "After that I was able to get my breaking stuff down in Nola, and get everything back on line, and keep working toward the catcher, and throwing strikes."
The arrival of Steckenrider means the Marlins have three of their Top 30 prospects, per MLBPipeline, on their active roster. Lefty reliever Jarlin Garcia and shortstop J.T. Riddle are ranked fourth and 12th, respectively.
Phelps is one of Miami's most dependable and versatile pitchers. His 20 appearances are second on the club to Brad Ziegler's 21, and he's logged 22 innings with 24 strikeouts and a 3.68 ERA.
• Wei-Yin Chen, on the disabled list since May 5 with left arm fatigue, received a PRP (Platelet-rich plasma) injection Tuesday. The injection helps reduce pain and assist the healing process. Chen is dealing with a partial ulnar collateral ligament tear, and as of now, there is no discussion about whether he needs Tommy John surgery. A year ago, Chen had a PRP injection and missed two months with a similar injury.
• Third baseman Martin Prado (right hamstring strain) is starting to swing the bat and do some tee work, but he remains weeks away from returning. Infielder Miguel Rojas (fractured right thumb) had the cast removed, and he remains likely out until around the All-Star break.
Joe Frisaro has covered the Marlins for MLB.com since 2002. Follow him on Twitter @JoeFrisaro and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.