Walker could be called up to start Tuesday, according to MLB.com's Greg Johns.
The Mariners have not announced a starting pitcher for Tuesday's game as of yet, and Walker would be pitching on normal rest that day, so he would seem like a natural fit to fill the spot. Walker has made three starts with Triple-A Tacoma since being demoted in late July, and tossed 6.1 scoreless innings his last time out. Walker was sent to Tacoma partly for an attitude adjustment, but both team and player are better off with him pitching at the top level, and it appears the Mariners are on the verge of giving him another shot.