As training camp reaches its midway point in Green Bay, there's no shortage of battles for open roster spots.

Some players appear to have solidified their spots on the 53-man roster—guys like Derek Sherrod, Sean Richardson and Jarrett Bush—while others are still up for grabs.

There's still three weeks of practice and three preseason games for players on the roster bubble to secure themselves a job.

Here's the places where the most uncertainty still exists:

1. Two or Three Quarterbacks?

The Packers have to answer two questions at the quarterback position: A) Who will be the backup to starter Aaron Rodgers? And B) Will they carry three quarterbacks?

Matt Flynn and Scott Tolzien are engaged in a duel to find out who will be Rodgers' apprentice in 2014 with neither player as of yet establishing himself as the clear-cut front runner.

Tolzien can come away from the team's preseason opener feeling good about his performance against the Titans, but he'll need more than one decent performance to vault ahead of Flynn.

Flynn, meanwhile, did nothing special in his playing time during the first exhibition game, but he gets the benefit of the doubt having played in the worst weather conditions of the evening.

At the end of August, the Packers will have to ask themselves whether they can afford to keep three quarterbacks on the roster at the expense of cutting a player at another position.

2. Six or Seven Defensive Linemen?

B.J. Raji, Mike Daniels, Datone Jones, Josh Boyd and Kyhri Thorton are assured spots on the Packers' regular-season roster.

The hamstring injury to Letroy Guion, which has kept him out of action since the beginning of training camp while on the team's Non-Football Injury list, has complicated matters.

Guion was expected to be a run-stuffing part of the team's plans when he was signed as a free agent in the offseason.

It would appear, however, that Guion may be losing ground to undrafted rookie Mike Pennel, who has turned heads at camp.

Even though the Packers run a 3-4 defense, they operate out of their nickel defensive package with only two defensive lineman more often than not.

Is it worth it to keep seven defensive linemen when frequently only two are on the field at any one time?

3. Who's the Sixth Wide Receiver?

There's so much talent at the wide receiver position, it's almost a given that the Packers will keep six instead of five.

After Jordy Nelson, Randall Cobb, Jarrett Boykin and Davante Adams, spots five and six are open for competition.

Jeff Janis would seem to be a good bet for one of them despite being slowed by a case of Shingles that forced him to miss nearly two weeks of camp.

If the Packers were to cut Janis, there's a good chance they'd lose him as a waiver claim to another NFL team.

For the time being, it would appear as if Kevin Dorsey has the inside track on another roster spot.

Dorsey has more special teams return value than Myles White and has been more consistent that Chris Harper, who always seems like he's suffering from a case of the dropsies.

4. Fourth Tight End

Richard Rodgers, Andrew Quarless and Brandon Bostick seem to have jobs locked up.

There's no guarantee the Packers will keep more than three tight ends, but it's such a versatile position—with players able to line up in-line, out wide, in the backfield and provide special teams help—it seems to be a good bet they'll keep four.

Colt Lyerla would have seemed to be a good candidate before the start of training camp, but his injury has him destined for the practice squad, injured reserve or possibly, even out the door.

The final spot would appear to come down to between Ryan Taylor and Jake Stoneburner.

Taylor is the more experienced player and the better special teams contributor, while Stoneburner is more potential-laden, better downfield receiving threat.

5. Sixth Cornerback

Sam Shields, Tramon Williams, Davon House and Casey Hayward aren't going anywhere. Neither is special teams ace and backup extraordinare Jarrett Bush.

If the Packers keep six, it's going to come down to sixth round draft choice Demetri Goodson and 2013 holdover Jumal Rolle.

With a year of professional experience under his belt, Rolle seems to be the more pro-ready player, ready to contribute if forced into action.

Goodson, meanwhile, is the rough-around-the-edges rookie that might have the higher ceiling.

It isn't often that the Packers part ways with their draft picks in their first year, but it's interesting that Rolle is actually younger (24) than Goodson (25).

6. Sixth Outside Linebacker

Julius Peppers, Clay Matthews, Mike Neal and Nick Perry are assured of roster spots. And the Packers probably aren't going to give up on Carl Bradford in his rookie year.

But the sixth outside linebacker is anyone guess.

Both Andy Mulumba and Nate Palmer enter their second seasons in the NFL, but neither is guaranteed to stick around.

Mulumba seemed to be the better of the two a year ago, but Palmer seems to bring more special-teams value.

Undrafted rookies Adrian Hubbard and Jayrone Elliot both have some raw potential, but is it enough to make the 53-man roster?

Quick Thoughts on the Rest of the Roster

7. Raijon Neal is making a nice run at a roster spot, but it would appear too much to ask to unseat DuJuan Harris, unless there's an injury at running back.

8. Following the injury to Don Barclay, Derek Sherrod, Lane Taylor and Corey Linsley have asserted themselves as the top three backups on the offensive line.

9. Joe Thomas has had a nice training camp, but at this point in his development, there seems to be a better chance he makes the practice squad than the 53-man roster.

10. If Chris Banjo makes the roster for a second consecutive season, he'll have to be an absolute special teams stud.

11. The specialsts—Mason Crosby, Tim Masthay and Brett Goode—are locked in to their roster spots.

Brian Carriveau is the author of the book "It's Just a Game: Big League Drama in Small Town America," and editor at Cheesehead TV and its "Pro Football Draft Preview." To contact Brian, email [email protected].