Bills training camp 2015: Mario Williams among five not participating on Day 1

The Buffalo Bills already had two free roster spots heading into 2015 training camp, and now they'll be without five more players when they hit the practice field for the first time on Friday morning.

Mario Williams, Leodis McKelvin, and Dan Carpenter will all start the season on the Active/Non-Football Injury list, while reserve tight end Chris Manhertz and undrafted rookie cornerback Cam Thomas were both placed on Active/Physically Unable to Perform.

Some #Bills news today prior to the team taking the field for the first practice tomorrow morning. pic.twitter.com/6NHlcZLHfS

— Buffalo Bills PR (@BuffaloBillsPR) July 30, 2015

The team did not disclose specific reasons for the listings. Players took physicals and participated in conditioning tests today, so one might guess that their landing on a non-participation list stemmed from their performance in either of those two venues.

Carpenter is coming off of undisclosed offseason surgery. The same is true for McKelvin, who is coming off of an ankle repair that cost him the final six games of the 2014 regular season. Williams is the bigger enigma; Rex Ryan is known to run a veteran-friendly camp, however, so it's possible that the team is just easing their star pass rusher into the new year.

All five of these players are eligible to be restored to the active roster - and by extension, the practice field - at any point. Before we all go freaking out, it's important to realize that all five of these players may not miss much time at all. And for the three veterans, specifically, they probably don't need an entire camp's worth of practice time, anyway.