The Athletics optioned Harris to Triple-A Las Vegas on Monday.
Harris spent part of the offseason recovering from thumb surgery, but he returned to full health for the start of spring training. The 27-year-old probably needed a big showing in Cactus League play to secure a spot on the Opening Day roster, and his .584 OPS over 26 plate appearances ultimately didn't cut it. Harris is likely to handle an everyday role in the corner infield at Las Vegas.