MLB.com's Bill Ladson has the story in an article entitled, "Nats lefty Perez files for free agency". Perez played for $850,000 last season, and should be in for a raise after going (7-12) with a 4.34 ERA and 119 K's in 30 starts for the worst team in baseball. The Nationals' Opening Night starter has not ruled out a return to the team...