Davis has had numerous injuries, including arm surgery in 2010, as well as a minor heart problem and thyroid cancer in 2008. But he still can be an important swing man between the bullpen and rotation.
The Cubs came into the season without a left-handed starter. If Davis can regain his previous form, he'll give Mike Quade some flexibility while Wells and Cashner are out.
The Cubs have no commitment to Davis after he signed the minor league contract on Tuesday. He'll continue to build his pitch count at the Cubs' minor league facility in Mesa, Ariz.
A team source said that Davis already has built his pitch count up to 72.
Davis was one of three Arizona Diamondback pitchers to defeat the Cubs during a three-game sweep in the 2007 NLDS.
He has a 91-101 career record and 4.38 ERA in 12 major league seasons.