Ed Valentine of SB Nation's New York Giants site, Big Blue View, points out a column by ESPN's John Clayton, stating the NFLPA has not yet approved a proposed rule that modifies the league's current Injured Reserve policy and extends the trade deadline from Week 6 to Week 8.
Particularly, how things may play out for RB Rashard Mendenhall and NT Casey Hampton.
The proposed rule would allow a team to place a player on a new injury list that would rule them out of game action through Week 8, and prohibit them from practicing through Week 6 of the regular season. Along with that, it would extend the trade deadline from Week 6 to Week 8, seemingly in unison with the new injury designation.
Currently, a team has the option to place a player on the Physically Unable to Perform (PUP) list, which keeps them out of action for the first six weeks of the regular season. At that point, the player must be moved to the active roster, placed on the IR or released.
This new rule, if approved, could buy the Steelers another two weeks to allow Mendenhall or Hampton some extra time to progress with their rehabilitation assignments. This could be important to the Steelers because it would allow them to keep an extra player on the active roster for another two weeks.
Considering how good NT Steve McLendon looked in Pittsburgh's 24-23 loss at Philadelphia in the first preseason game, the Steelers can't feel too horrible about not having their starting nose tackle of the last 12 seasons. Hampton has been on the preseason PUP, meaning he's not counting against their roster. It's possible he could start the regular season on the PUP, meaning he would miss the first six weeks (five games, the Steelers have a bye in Week 5). Extending that out another two weeks would be an option if the Steelers felt their depth at another position would be sacrificed and that would be more detrimental than carrying two starting caliber nose tackles for another two weeks.
In Mendenhall's case, he's a three-down player, and it doesn't appear the Steelers have a back capable of playing on all three downs outside of him and Isaac Redman. Depending on his rehab progress, it would be less likely the team would want to hold him out for another two weeks if he's ready to play.
The rule is in place to allow teams more flexibility in making roster decisions. Some players get hurt early enough in the season where they could eventually return, but a team can't afford to use a roster spot on a player who will be out for two months, so he's placed on the IR. This wouldn't be used on a player like TE David Johnson, whose torn ACL and MCL will require several months of rehab.
This is all assuming, of course, the NFLPA approves these changes. The league can propose changes to current roster rules, but before being implemented, the union must approve them.
It doesn't seem clear why the union would oppose this, except that players placed on the IR have their contracts for that season fully guaranteed. It doesn't seem this new injury designation would provide a similar payment option. As Valentine points out, S Terrell Thomas's situation is uniquely fit for this rule. After tearing his ACL last year, he re-injured his knee in training camp, and is looking at an 8-10 week recovery time. He noted he doesn't want to risk further damage by pushing it more than he already has.
The team can either place him, a talented player, on the IR now, or keep him on the shelf until Week 8, right around when it's said he'd be recovered. He's done for the year if he goes on the IR.
There isn't a report on reasons behind the hold-up on the union's part, but this is right around the time teams would want to utilize that rule.