The Giants optioned Villar to minor-league camp Wednesday, Alex Pavlovic of NBC Sports Bay Area reports.
Villar was never a likely bet to make San Francisco's Opening Day roster, though he had a strong showing during spring training with three homers and a 1.093 OPS in 44 plate appearances. The 27-year-old had an .869 OPS at the Triple-A level last season but also struck out at a 26.6 percent clip, and he'll likely need to show improved contact skills to having any staying power in the majors.