Kelley cleared waivers and was outrighted to Triple-A Durham on Sunday, Marc Topkin of the Tampa Bay Times reports.
Kelley was designated for assignment by the Rays on Friday but will remain in the organization after passing through waivers unclaimed. The 29-year-old posted a 5.87 ERA, 1.43 WHIP and 11:6 K:BB over 15.1 major-league innings this season.