Ken Rosenthal of Fox Sports provided details on the player's decision:
Gallardo has been one of the most well-traveled pitchers in Major League Baseball. The 31-year-old has played for four different teams over the past four seasons, including the Brewers, Texas Rangers, Baltimore Orioles and Seattle Mariners.
Unfortunately for Gallardo, one reason he's been unable to stick anywhere more than one year is his performance, especially the past two seasons. The former All-Star has a 5.57 ERA and 1.55 WHIP in 51 appearances since the start of 2016.
Things got so bad for Gallardo with the Mariners in 2017 that he was moved to the bullpen on two separate occasions during the season.
It was a role that Gallardo started to embrace after getting comfortable with it.
"I'm going to do whatever I can to get guys out," Gallardo told MLB.com's Josh Horton in July. "No matter what the score is when I enter the situation that I'm in. We all know that everything can happen in this game."
Milwaukee can use that versatility to its advantage by using Gallardo to fill whatever its biggest need is, whether it's help in the rotation or the bullpen.
Gallardo is at a career crossroads. He's still young enough to be a productive pitcher, but the results have been bad enough for two straight years that he needs to bounce back to possibly secure one more multiyear deal.