The NFL Players Association filed a grievance on behalf of Richard Seymour on Friday, a source told the Boston Globe. The grievance reportedly claims that the Raiders were not within their rights to send him a "five-day letter," which said he could be suspended for the season if he doesn't report to the team by Tuesday. The NFLPA plans to argue that the "five-day letter" rules do not apply to players that are traded. If Seymour wins the grievance, it's possible that last weekend's trade in which the Raiders swapped a 2011 first-round draft choice to the Patriots for Seymour won't be consummated.