As NFL investigator Ted Wells prepares to visit South Florida to interview Dolphins players who may have knowledge about the accusations of tackle Jonathan Martin, the NFL Players Association has taken extra steps to protect them. Per a league source, the NFLPA has retained attorney Richard Smith to represent the interests of any players who ultimately face accusations of wrongdoing as a result of the investigation. Smith had been retained by the union last year to represent any players accused of wrongdoing in connection with the Saints bounty scandal. Via a series of successful legal maneuverings, all player discipline ultimately was scrapped by former Commissioner Paul Tagliabue. The source says that suspended guard Richie Incognito separately has retained attorney Mark Schamel. Most recently, Schamel represented Broncos linebacker Von Miller in connection with his effort to negotiate a six-game suspension for violating the league’s substance-abuse policy. Miller reportedly conspired with a sample collector to pass drug tests.