Estevez was optioned to Triple-A Albuquerque prior to Monday's game against the Braves.
The Rockies needed to clear room on the roster for Monday's starter Chad Bettis, and Estevez was the resulting roster casualty. He pitched solid in his most recent stint with the big club, registering four scoreless innings to help lower his ERA to 6.53 on the season. He'll continue to provide organizational relief depth now that he's back in Triple-A.