The 30-year-old southpaw is trying to make a comeback with Baltimore after bouncing around the big leagues since he was traded by the Tigers to the D-backs almost two years ago.
The 2003 National League Rookie of the Year is 72-69 with a 4.17 ERA over a nine-year career. He has not appeared in the big leagues with Baltimore, which apparently still believes he can start at the Major League level. The Orioles signed him in March after he was released by Philadelphia.
There was a difference in opinion between the Orioles -- who said in late April that Willis left the Triple-A Norfolk team without permission -- and the pitcher, who said he had permission to leave the club.
Whatever the case may be, Willis is expected to spend time at extended Spring Training in Sarasota, Fla., building up his pitches since he did not feel comfortable working as a reliever. The news was first reported by ESPN.com.
Of Willis' 205 career appearances, 202 have been as a starter. He pitched twice in relief in 2010 (once with Detroit, once with Arizona) and once in 2008 (with Detroit).