Stolmy Pimentel is listed as the starter for the Altoona Curve tonight, so that's where he'll begin his rehab assignment for his extremely convenient sprained ankle. (Tim Williams writes that Pimentel will pitch one inning.) Pimentel, of course, is out of options, which means the Pirates couldn't send him to the minors except for rehab assignments. They've treated him as a Rule 5 pick the entire year, and that came to a head last week when he essentially ruined what had been a one-run game against the Tigers.
So now, he'll head to Altoona and pitch a couple games, and the Pirates will likely move him back to the majors after September 1, when you can really promote whoever you want without serious consequences. Pimentel remains an asset who's struck out 10.5 batters per nine innings in his first full year in the big leagues. This season probably suggests there's a pretty good big-league reliever in there somewhere. But his out-of-options status this year has been frustrating. He has limited experience at Triple-A, and he probably could have used more.