Union files grievance for Seymour

The NFL Players Association filed a grievance on behalf of Seymour yesterday, according to a source familiar with the union’s thinking. The grievance claims that the Oakland Raiders were not within their rights to send him a “five-day letter,’’ which noted he could be suspended for the season if he doesn’t report to the team by Tuesday.

The grievance calls for an expedited hearing, so a decision can be made before Tuesday’s deadline.

The NFLPA plans to argue that the “five-day letter’’ rules do not apply to players who are traded from one team to another. Part of the argument appears to be that since Seymour has not taken a physical, the final step to presumably consummating the trade, the Raiders are not within their rights to send the letter.

If Seymour wins the grievance, it’s possible that last Sunday’s trade in which the Raiders swapped a 2011 first-round draft choice to the Patriots for Seymour won’t be consummated.

Early this morning, citing sources familiar with the negotiation, ESPN’s Adam Schefter reported that Seymour and the Raiders were in the final stages of planning his arrival in Oakland. The report stated that Seymour could arrive as early as today.

Meanwhile, Raiders coach Tom Cable said he has not let the drama become a distraction.

“Until we have some facts on what is or isn’t going to happen, I’ve really felt like it’s not an issue until we have something concrete that we know will happen,’’ Cable said to the Bay Area media yesterday. “So, with that in mind, it’s just been business as usual in terms of getting this team ready to play.’’

Cornerback Nnamdi Asomugha told reporters players are hopeful Seymour will arrive.

“We come in hoping to see him here and then we’re promptly disappointed,’’ Asomugha said.

Green has filled in for Seymour throughout his career. In the 2004 postseason, Green started three games in place of an injured Seymour, picking up a sack/forced fumble in the AFC title game against Pittsburgh. Three seasons later, Green started a career-high 10 games when Seymour was unable to play because of offseason knee surgery.

Those various moments helped prepare Green, he said.

“Yeah, all the things that I’ve been doing since I’ve been here, getting an opportunity to fill in at [right] defensive end and all the things I’ve done in the past,’’ Green said. “It’s another time to go out there and another opportunity to get better as a football player.’’

Mayo, 23, was selected by his teammates, joining Vince Wilfork, offensive captains Tom Brady and Randy Moss, and special teams captain Sam Aiken.

“We still have some veteran leadership on the defensive side of the ball and the offensive side, so I’m not worried about it at all,’’ Mayo said.

“One thing about Rodney is that he doesn’t hold his tongue for nobody, and he always speaks his mind, so if he said that he obviously felt that way,’’ said Sanders with a laugh. Harrison, who retired in June, was Sanders’s mentor and Sanders has tried to follow in his footsteps.

Sanders has emerged as a leader in the secondary and acknowledged it is strange to have the most experience in the secondary since he only joined the Patriots in 2005.

“Time goes by fast,’’ said Sanders. “It still feels like I’m a rookie. It’s a change for me being one of the leaders in the secondary, and I’m going to do what I can to lead and make sure everybody is ready to go.’’

With Ellis Hobbs in Philadelphia, Maroney will get some extra chances.

“It is just another way to get the ball in people’s hands,’’ said Maroney, who had one return for 35 yards in exhibition play. “It’s the first game. I’m real excited just to get out there and help the team in any way possible. If it’s not playing running back, it’s kickoff return. If it’s not doing kickoff return, it’s doing running back or whatever [coach Bill ] Belichick asks of me. It’s just getting the opportunity to play.’’

Mike Reiss of the Globe staff contributed to this report.