The Rockies claimed Kelly off waivers from the Rangers on Monday.
Colorado designated left-hander Josh Rogers for assignment to clear a spot on the 40-man roster for Kelly, a 24-year-old southpaw who offers more long-term upside but has struggled mightily in the minors this season. Between stops with Triple-A Round Rock and Double-A Frisco, Kelly has posted a 9.35 ERA and 24:22 K:BB in 17.1 innings.