Per various folks in the Twitterverse, Craig Gentry has been activated from the disabled list, and Darren O'Day has been optioned to AAA Round Rock.
Gentry was put on the 7 day concussion disabled list, and was originally scheduled to be activated prior to yesterday's game. However, Alexi Ogando's short outing resulted in the bullpen having to log a bunch of innings on Tuesday, so the Rangers opted to wait until today to make the move, in order to have an extra arm available in the pen.
Why make the move today, during an off day, rather than tomorrow? Because O'Day can't be recalled (barring an injury) for ten days once he's sent down, so by sending him down today, they start the clock ticking immediately on when he can return to the majors.
Gentry is expected to resume his role as the team's centerfielder against lefthanded starters, along with being a pinch runner and defensive replacement for late in games.