If RG3 is healthy, Rex Grossman may not make Redskins’ roster

In 2012, Rex Grossman never played in a regular-season game. But he did play an important role on the Redskins, serving as the veteran mentor on a team whose other two quarterbacks, Robert Griffin III and Kirk Cousins, were rookies. In 2013, Grossman may have no role to play on the Redskins at all. Rich…