Matt Cassel, Seantrel Henderson moving onto Bills' roster bubble

The end of Buffalo Bills minicamp Thursday began a six-week slow period for coaches, players and reporters.

As I've done for the past three summers, I'll fill your football fix during that downtime with a series examining which players are on the roster bubble entering training camp.

Here's the exercise: I slice the roster into three parts. The first group is players that are locks or near-locks to make the roster. The second group is players "on the bubble," or who have a realistic shot of either making the roster out of training camp or getting cut. The final group is "long shots," or players who will be hard-pressed to make the squad.

I'll assign a percentage chance of each player "on the bubble" making the team. It's not scientific, and if you add the percentages up at the end of the series, they'll likely lean towards more than 53 players making the team to account for injuries.

The Bills' "bubble watch" will start Monday, but as a preview of sorts, here are two bigger-name players who will be included in the series that I might not have considered "on the bubble" a month ago:

QB Matt Cassel: The Bills have a quarterback "competition" but in three OTA practices and three minicamp sessions open to reporters this offseason, it was more of a test of which quarterbacks could make the fewest mistakes than it was a race between three consistent, competent NFL quarterbacks. I would give EJ Manuel the slight nod as the "winner" from spring practices but Cassel was the clear "loser" of the group. There wasn't a practice open to reporters where Cassel stood out among his peers, while there were at least one or two sessions where he was just downright bad. I went into OTAs thinking Cassel had the best chance to be the opening day starter, given his level of experience, but I now question if he will make the roster. The Bills can wipe his $4.15 million base salary off the books if they release him prior to the start of the regular season, an appealing option if Cassel's struggles continue into training camp.

OT Seantrel Henderson: I wrote Thursday about why Henderson has fallen behind Cyrus Kouandjio in the race to become the starting right tackle, but I'll take it a step further here: I believe Henderson's roster spot could be in jeopardy this summer. Rex Ryan saying Thursday that he expects the Bills to sign veteran Wayne Hunter is a giant red flag for Henderson. Ryan has a long history with Hunter and has noted his versatility as a potential swing tackle and sixth offensive lineman/tight end. If the season started today, I could easily see Ryan going with Cordy Glenn and Kouandjio as his starters and Hunter as a reserve lineman. That leaves Henderson on the roster bubble. Doug Marrone was able to get Henderson focused on football and was comfortable starting him 16 games last season, but Ryan's coaching staff doesn't seem to have the same confidence in Henderson.