Sanchez, 30, allowed 18 runs and 34 base runners in 13 2/3 innings for Pittsburgh this year. He made four starts and only once completed four innings of work. Plus, he was ejected once for intentionally throwing at a batter. That earned him a six-game suspension and a fine.
Since the start of last season, Sanchez has pitched to an 8.73 ERA and 2.145 WHIP in 78 1/3 innings for three clubs. He threw a no-hitter for the Giants against the Padres in July 2009 and was part of San Francisco's rotation for its run to the 2010 World Series title.
Wandy Rodriguez recently returned from a hamstring problem, taking Sanchez's rotation spot. The Pirates also have left-hander Francisco Liriano working his way back from a broken non-pitching arm. He has made three minor league rehab starts.
Morris, 26, has appeared in one game for Pittsburgh this season. He has allowed two runs in eight big-league innings dating back to last season. Morris has gone 2-2 with a 2.58 ERA in 87 1/3 innings at Triple-A in his career.