The well-traveled and often enigmatic Willis, who was 1-6 in 13 games as a starter with Cincinnati last season, was plaqued by inconsistency and arm soreness this spring, and admitted he didn't adjust well to his new role in the bullpen.
"I felt we owed it to him to give him a chance to go somewhere else and get hooked up," Phillies manager Charlie Manuel said of the decision to cut Willie loose now rather than later in the spring.
"I used to love to watch him pitch. I still do. He's a character. And he's a baseball person.
"His command was the big thing," Manuel continued. "But he's a gamer. He might land somewhere else and do well. I hope he does."
Willis allowed five runs in 2 2/3 innings this spring and had a 16.88 ERA. Although he pitched a scoreless inning on Thursday, he walked the first batter he faced on five pitches.
"We didn't feel, based on what we had seen out of him, that he was going to help us," said Phillies general manager Ruben Amaro Jr.
Amaro said he isn't certain how many lefties the Phillies will carry in their bullpen.
"I don't know if we need one [a second left-handed reliever]," Amaro said.
"In a perfect world, it would be great to have two or three leftties. But in a more perfect world, it would be great to have guys who are getting people out."
Since being traded to the Tigers in December 2007, Willis has pitched for three teams in the last five seasons.
The southpaw broke into Major League Baseball in 2003, helping lead the Marlins to a World Series title while nabbing National League Rookie of the Year Award honors. Willis went 14-6 with a 3.30 ERA during the regular season and also pitched 3 1/3 scoreless innings in relief against the Yankees in the Fall Classic.
Willis narrowly missed out on adding a Cy Young Award to his collection in 2005, finishing second to Chris Carpenter. Willis notched career bests in wins (22), ERA (2.63), strikeouts (170), complete games (seven) and shutouts (five) in that '05 campaign.
A two-time All-Star with the Marlins, Willis hasn't posted a sub-5.00 ERA since putting up a 3.87 mark with Florida in 2006.
Jim Hawkins is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.