When the Patriots returned to their practice field Tuesday, intrigue tagged along, in the form of players who weren't taking part.

Most of the names of the absentees were expected, but the one who took most observers by surprise was Shea McClellin. The veteran linebacker has been on injured reserve all season with what is believed to be a concussion, but began practicing again on Oct. 18, when the Patriots named him as one of their two players designated for return from IR.

It appears now, however, that McClellin's status is in serious doubt.

McClellin would have been eligible to play this weekend at Denver, and his presence on the roster was expected to provide much-needed depth, especially with the loss of linebacker/co-captain Dont'a Hightower to a pectoral injury. Hightower underwent surgery last month and was among the no-shows. He has yet to be placed on IR by the Patriots, but that seems imminent, according to media reports.

With McClellin apparently no longer a consideration for contributing in 2017, the Patriots have just one designated-to-return option left. Candidates include wide receiver Malcolm Mitchell and defensive lineman Vincent Valentine. If Hightower is, as expected, placed on IR, he, too, could conceivably be brought back during the playoffs, if New England is fortunate to extend its season into January. Neither Mitchell nor Valentine has suited up yet for a practice. Given how the McClellin situation appears to have unfolded, the Patriots might be more cautious with whom they choose to bring back.

Meantime, other absent players Tuesday included wide receiver Chris Hogan (right shoulder), right tackle Marcus Cannon (left ankle), defensive tackle Malcom Brown (ankle), and left tackle Nate Solder. It's unclear why Solder did not take part, but with both starting tackles out of action – at least for today – it was curious to see rookie Andrew Jelks suit up for the first time. Jelks has been on the non-football injury list (NFI) all season with a knee injury.

Meantime, Brown's injury could be a potential concern if the appearance of two new defensive linemen at Tuesday's practice is any indication. One of those two new players is reportedly a veteran who's bounced around the NFL since 2009.

Since today's practice is technically an extra day of work, outside the normal Wednesday through Friday NFL routine, the Patriots are not required to issue an injury/participation report until tomorrow.