Training camp is arguably the most stressful time of the year for many NFL players. Think about if you had to re-interview for your job every year against about 30 new applicants.
That's training camp for most players, every single year. The incumbent players at the greatest risk of being replaced, as well as the new guys with the best chance of making the team, make up the roster bubble.
These are those guys.
Stefan Logan, KR/RB
Logan looked like one of the best return men in the game in 2010.
In 2011, he showed an utter lack of explosion. His longest kick return was only 42 yards (compared to 105 yards in 2010), and his longest punt return was for 28 yards (71 in 2010).
Averages were down, fumbles were up, and it started looking increasingly silly for the Lions to spend a roster spot on such pedestrian production.
There is no heir apparent to Logan's return position right now, but if the Lions find a position player that does Logan's job as well as he does, Logan could be gone.
Maurice Stovall, WR/ST
Stovall is another special teams guy who might lose out to a younger player with upside in another phase of the game.
Stovall wasn't nearly as visible as Logan, as a kick/punt coverage team specialist, but he was still quite good.
Problem is, Stovall takes up a wide receiver slot, and there's one less of those available with Ryan Broyles on the roster.
The Lions certainly need special teamers, but they also need talented guys in other phases. As a result, they might opt for project players who can play special teams, rather than veteran guys who only play special teams.
Jonte Green, CB
The last of three draft picks the Lions spent at cornerback this year, Green certainly has the upside to stick around, but he doesn't have the relative polish that Bill Bentley has, or the size and raw athleticism Chris Greenwood has.
This will come down to a camp battle, but Green seems like an easy choice for the practice squad unless he makes an impact in camp. The Lions don't seem like a team excited to carry three rookie cornerbacks on the roster.
Travis Lewis, LB
Like Green, Lewis is a low draft pick (seventh round) with fellow rookies at the same position drafted before him.
Lewis, however, has only a single rookie to battle with, and a lot less competition for depth. The Lions' linebacker situation is almost the polar opposite of their cornerback situation: there is tons of depth at cornerback, but no clear starters, compared with three definite starters at linebacker and no certain depth.
Lewis appears to have an open roster spot ready for him, as long as he can beat out the next guy on this list.
Ashlee Palmer, LB/ST
Palmer represents seemingly the stiffest competition for Lewis at the sixth linebacker spot.
But Palmer is a quality special teamer, and not especially valuable on the defense. Lewis is a project player who may bring value to the defense relatively soon.
The question here might be, again, whether the rookie project can match the veteran special teamer at his own game. Although, in this case, it's also possible the Lions enter the season with seven linebackers. It's hardly unheard of.
Kellen Moore, QB
I spotlighted this already, but it bears repeating. Moore seems like a shoo-in as third quarterback. What doesn't seem like a shoo-in is a roster spot allotted to a third quarterback.
This should be all on Moore. If he shows potential, the Lions will make room for him. If not, the decision might get a little tougher.
Patrick Edwards, WR/KR
By far the most impressive UDFA on the roster right now is Patrick Edwards.
The quick-footed receiver out of Houston has gotten plenty of attention in OTAs and minicamps so far, playing effective the exact slot position envisioned for Ryan Broyles.
Broyles, of course, is still recovering from his ACL injury, and in his absense, Edwards did pretty much everything the Lions were expecting out of Broyles.
But what makes Edwards most dangerous is his ability to return punts. That makes him a far greater threat to Stefan Logan than Broyles.
Andre Fluellen, DT/DE
I say every year that it's Fluellen's last year, and every year he comes back on another one-year deal.
I could understand last year, as Nick Fairley was injured and nobody knew when he would play (as it turned out, very little all season).
This year, Fluellen might make the roster on account of Fairley's likely upcoming suspension, but I have to wonder what happens to his roster spot when Fairley returns. Maybe this year will finally be the year.
Jason Fox, OT
Jason Fox needs to have a healthy training camp and a healthy 2012 season. If he can do that, he's big piece in the Lions' offensive line, and a possible future starter at right tackle.
But Fox has been healthy and available for about four games out of 33 since he was drafted. If his health doesn't hold up this year, his roster spot won't, either.
Corey Hilliard, OT/G
Don't let me say anything bad about Corey Hilliard, who has pretty well been the Lions' primary depth player at just about every offensive line position.
But with Riley Reiff on the roster, Fox (maybe) coming back from injury, and Johnny Culbreath getting his first real opportunity to show his stuff after what amounted to a redshirt rookie season, Hilliard might have trouble earning his way in.
Which reminds me...
Johnny Culbreath, OT/G
The offensive line equivalent of Sammie Hill, Culbreath is a big, strong guy from a tiny university (South Carolina State, which is a smaller school than it sounds like).
He has raw physicality, and now a year of NFL experience (albeit experience spent on IR), and with those two things, we really have very little idea what to expect from Culbreath.
With the apparent logjam of players at tackle now, Culbreath's best shot at the roster may be as a converted guard.
Joique Bell, RB
Bell is a speedster out of Wayne State who perhaps has the most to gain from a potential injury in the running back corps.
Barring that, as an undrafted player in his second year, Bell is looking at probably having to beat out Keiland Williams to earn a spot on the team.
Bell's game is a lot closer to Jahvid Best than it is Williams, so perhaps it will be in the Lions' interest to keep him on board as insurance for the oft-injured Best.
Keiland Williams, RB
As the other side of the running back equation, Williams was, at times, the Lions' top running back in 2011.
He performed admirably at times, but there is little doubt the Lions would have expected more from their injured backs.
With that injured talent returning to the roster, Williams is back down to the bottom of the depth chart to battle it out with Bell. But unlike Bell, Williams will likely have to prove his worth in his ability to handle short-yardage situations.
Erik Coleman, S
The guy who was supposed to be the veteran safety to push Amari Spievey and the backup plan in case of injury, Coleman actually succumbed to injury himself after four games.
The Lions are giving him another shot, as they still need a true veteran presence (even on the bench) at safety. But he's likely fighting for his spot with...
Sean Jones, S
Another solid veteran player, Jones has been a starter throughout his career, and at age 30, he could give the Lions a boost at safety, however slight.
I doubt the Lions are ready to give up on the young Spievey just yet, so my guess is that Jones and Coleman battle it out for the job Coleman was supposed to do last year.
Everette Brown, DE
If the Lions are able to get something valuable out of Brown, it will be like Lawrence Jackson all over again.
Jackson was a first-round pick essentially labelled a bust (by the new Pete Carroll regime) and shipped out of Seattle for a Lions sixth-round pick. He has since become a valuable rotational defensive end, though perhaps not the flashiest or most imposing player on the team.
Brown, similarly, was a second-round pick for the Carolina Panthers in 2009. He was released after two seasons with the Panthers, played a year for the San Diego Chargers, and was released again.
That makes Brown a fourth-year player on his third different team, relatively atypical for a second-round pick. But like with Jackson, it could be that Brown just needs a place to shine and will contribute to the rotation.
It may also be that he fizzles out and his dream of an NFL career ends in Detroit.
Ben Graham, P
Graham did such a fantastic job as the Lions' emergency mid-season punter last year, the Lions brought him back on a one-year deal.
And while I fully expect the Lions to move forward with young second-year punter Ryan Donahue, who was perfectly respectable before getting injured, Graham has a shot of making the team that is small, but not impossibly so.
If Graham doesn't make the team, expect the Lions to release him early, giving him time to find a new team (like they did with Dave Rayner last year).