Foster Griffin is trade chip and extension candidate for Nationals

Talk about multi-faceted: All-Star left-hander Foster Griffin is both a valuable trade chip and a contract extension candidate for the Nationals.

The Wild Card-contending Nationals begin a critical four-game series in Atlanta tonight that could shape if they are buyers or sellers at Monday’s Trade Deadline.

According to MLB.com’s Mark Feinsand, per a source, a contract extension between…