Bass was designated for assignment Thursday, Jeff Wilson of the Fort Worth Star-Telegram reports.
The Rangers needed to clear a spot on the 40-man for Miguel Gonzalez, whom they acquired in a deadline deal Thursday. Bass was the casualty and will now be subjected to waivers before potentially returning to the Rangers' organization. Over 75.1 innings at Triple-A Round Rock this season, Bass posted a 4.18 ERA and 1.42 WHIP.