BALTIMORE -- Mac Williamson didn't have a choice the last time the Giants designated him for assignment. This time he did, and he decided to become a free agent.Williamson cleared waivers for the second time in just over two months and elected free agency, so he can pick from the 29 other teams as he looks for a fresh start and another chance to establish himself as a big leaguer. He had previously cleared waivers and been outrighted to Triple-A Sacramento, working his way back up to the big leagues for a brief audition.