McGuire was designated for assignment Monday, Stefan Stevenson of the Fort Worth Star-Telegram reports.
McGuire had been claimed by the Rangers off waivers Friday and was immediately optioned to Triple-A Round Rock. If he clears waivers, he'll likely remain at the same level. The move opens up a spot on the 40-man roster for the return of Elvis Andrus (elbow) from the 60-day disabled list.