OAKLAND, CA - JUNE 05: Derek Holland #45 of the Texas Rangers pitches against the Oakland Athletics during the first inning at O.co Coliseum on June 5, 2012 in Oakland, California. (Photo by Jason O. Watson/Getty Images)
Sullivan says that the Rangers are expected to purchase the contract of reliever Tanner Scheppers to replace Holland on the 25 man roster. There's no word as of yet what move would be made to clear a spot on the 40 man roster to make room for Scheppers.
Holland has had a couple of problematic starts in a row where he was attempting to pitch in a weakened condition, and the Rangers apparently want to make sure he's 100% before he pitches again. There is no word yet about who will take Holland's start on Saturday, but at this point, my guess on this would be either Robbie Ross making a spot start or someone from the minors -- likely Martin Perez -- coming up for a spot start.
More on this when it develops...
UPDATE -- Alexi Ogando is going to start this weekend, and John Gaub has been designated for assignment to make room for Scheppers on the 40 man roster.