A 2008 All-Star, Marmol had his best season in '10, when he posted 38 saves with a 2.55 ERA in 77 games and finished a league-most 70 games. But control issues have plagued him since. Reds Minor League pitching coordinator Mark Riggins was the Cubs' pitching coordinator from 2008-10 and their pitching coach in 2011.
"His best success was when Mark was there," Reds general manager Walt Jocketty said. "Mark wanted us to try and sign him. Because of his relationship with Marmol, we were able to sign him."
Once Marmol is done working in Arizona with Riggins and rehab pitching coach Tom Brown, he could likely go to Triple-A Louisville.
From 2011-14, Marmol has a 4.23 ERA, a 1.53 WHIP and has averaged 6.9 strikeouts per nine innings pitched. This season for Miami, he had 10 walks and 14 strikeouts over 13 1/3 innings.
Reds manager Bryan Price hoped that the club's coaches could help fix Marmol's control issues.
"One thing I realize is there have also been a lot of talented people who have worked with him in the past that have had their own successes or failures with him," Price said. "I'm sure his career is not based on a lack of good coaching. The bullpen position is such a volatile position and such a hard one to nail down with guys who can have long runs of consistent success."
The Reds have had issues with their bullpen this season, as its 4.78 ERA is ranked last in the National League. If Marmol is able to find his control in the Minors, he could become an option as relief help later this season.
"There is no question about his arm strength or health," Jocketty said. "It's more about his command. We'll see what we can accomplish these next few weeks."
The addition of Marmol is the latest of several Major League veterans who have been signed to Minor League deals recently. Former Braves lefty Jair Jurrjens and ex-Reds lefty Matt Maloney made deals last week, and the club has also brought in outfielder Shelly Duncan and catcher Lou Marson.
"We're trying to get the Louisville club a little stronger," Jocketty said. "Guys with Major League experience might be able to help us up here at some point."
The Reds have lacked depth with potential Major League ready callups this season.
"Sometimes you're catching lightning in a bottle, somebody has figured something out with their career or finally gets all the way healthy and could be more productive than anticipated," Price said.