The former first-round pick is relishing a chance to stick in the majors with the team that drafted him in 2006. Milwaukee called up the right-hander from Triple-A Nashville this week to help bolster the bullpen.
Jeffress has been suspended twice for violating the minor league drug policy, which he has said was for marijuana use. He has also suffered from debilitating seizures.
Now, the new father describes himself as being "in a very good place."
"I have a little girl now, 5 1/2-months old. I'm very clean and sober. I've been very well," Jeffress said.
Selected 16th overall in 2006, Jeffress has had an unexceptional major league career so far.
Jeffress is 3-1 with one save and a 4.47 ERA in 50 games, playing in parts of five seasons with the Brewers, Royals and Blue Jays. He might be best known for his inclusion in the six-player deal that brought ace Zack Greinke from Kansas City to Milwaukee in December 2010.
Jeffress had a 10.80 ERA in three innings with Toronto early this season before declining a minor league assignment April 16. He signed a minor league deal two days later with Milwaukee.
General manager Doug Melvin drafted Jeffress eight years ago. Jeffress considers his return to Milwaukee a homecoming.
"They stuck with me for a long time," he said. "I never thought I would be back. ... I know my time here was a great experience. It was home for me."
A low point came about two years ago when he was toiling in the minors and thought about quitting the game. At one point, he had a seizure on a plane during a road trip.
The seizures, Jeffress said, typically happened in the mornings. Doctors didn't know what was causing them until he spent a week at Women & Children's Hospital of Buffalo, where he suffered a seizure during his stay. He was put on an extended-release medication that has helped control the seizures.
In the Milwaukee bullpen, Jeffress will be relied upon to add a power-throwing presence in the bullpen. He had 45 strikeouts in 41 2-3 innings in the minors while walking 18.
Jeffress is ready for any role assigned by manager Ron Roenicke.
"He's always got to make sure he's doing the right things," Roenicke said. "Hopefully that's what we see here."