Simpson, who turns 24 on May 20, made 30 starts in 56 Minor League appearances from '11-'12, getting as far as High Class A Daytona last year. Overall, he went 5-17 with a 6.42 ERA, 120 strikeouts and 89 walks in 161 1/3 innings. He posted an ERA of 5.72 or higher at each level along the way.
Willis signed a Minor League deal with the Cubs in January, ending the retirement he announced last July after a brief stint with the Orioles' Triple-A affiliate in Norfolk. The 2003 National League Rookie of the Year Award winner made one Cactus League appearance this spring, on Feb. 25 against the Dodgers. He issued a walk, then exited with tightness in his left shoulder while facing the next batter.
Originally an eighth-round Draft pick by the Cubs in '00, Willis won 46 games with a 3.27 ERA for the Marlins from '03-'05, but has struggled with injuries and poor performance in recent years. He last pitched in the Majors in '11, when he made 13 starts for the Reds, posting a 5.00 ERA.
The Cubs also released catcher Michael Brenly, the son of former team broadcaster Bob Brenly. The younger Brenly, 26, hit .227 with six home runs and 28 RBIs for Double-A Tennessee last season.
Bob Brenly left the Cubs this offseason to broadcast games for the D-backs, the team he managed to the '01 World Series title.
Gene Duffey is a contributor to MLB.com. Andrew Simon is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.