Burton asked for and was granted his release, Jeff Wilson of the Fort Worth Star-Telegram reports. Burton posted a 0.90 ERA and 9.9 K/9 over 10 innings for Triple-A Round Rock, and he presumably hopes to find an organization that will give him a shot in the majors. He has 361 innings of big-league experience, owning a 3.44 ERA, 3.85 FIP, 4.22 xFIP and 7.6 K/9.