The 21-year-old right-hander will begin serving his suspension immediately.
Best, who was signed by the Phillies as a non-drafted free agent in June 2008, is currently on the rookie league Gulf Coast League Phillies roster. Converted from an outfielder to a pitcher before the 2009 season, Best went 1-1 with a 7.04 ERA in 7 2/3 innings of work for the GCL Phillies last season.
Jon Star is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.