SANTA CLARA, Calif. -- Patrick Willis may have a slightly different look in the first half of the upcoming season.During Tuesday's organized team activity, Willis was playing the "Mike" inside linebacker spot usually occupied by NaVorro Bowman in the 49ers' 3-4 defense. Bowman is likely out until midway through the season as he recovers from a torn ACL. Michael Wilhoite, the leading candidate to take Bowman's spot in the staring lineup, took most of the first-team repetitions Tuesday in the "Jack" inside linebacker spot Willis played last year.