The Athletics outrighted Jackson to Triple-A Las Vegas on Tuesday after he cleared waivers.
Jackson lost his spot on Oakland's 40-man roster Saturday, when the Athletics needed to clear room for right-hander Alex Speas after acquiring him from the White Sox. Though he notched 28 holds and four saves for Oakland over the past two seasons, Jackson struggled mightily in spring training to earn a demotion to Triple-A to begin the season. The Athletics elected to designate him for assignment after Jackson failed to show much improvement at Las Vegas; he was touched up for one earned run on two hits and five walks over two innings through his first two appearances in the Pacific Coast League.