In the days leading up to Training Camp, we will take a look at the most pressing questions facing each position group. Today, we look at the offensive line, a group that returns just three starters from last season ...

1. Who Starts At Guard?

Over the past few seasons, the Eagles' coaching staff hasn't had to worry much about who the team's starting guards would be. When healthy, Evan Mathis and Todd Herremans combined with center Jason Kelce to form one of the stronger interior offensive lines in the league. Of course, both starting guards were released during this past offseason, and now the biggest question facing the position group regards which players will be able to step up and claim the starting jobs.

One of the more prevailing thoughts about why the Eagles felt comfortable moving on from Mathis and Herremans is that the coaching staff really liked Allen Barbre, a sturdy, versatile offensive lineman who has performed very well in spot duty for the Eagles since his arrival in 2013. Barbre was set to be "sixth-man" of the Eagles' offensive line last season due to his ability to play guard or tackle, but an ankle injury against Jacksonville in Week 1 landed him on Injured Reserve. He was signed to a three-year contract extension in June of 2014, and now it looks like he will be called upon to step in as a starting guard.

The other starting guard job is more of a battle to watch. Among the possibilities are Dennis Kelly, Andrew Gardner and Matt Tobin, a trio of younger players who can play both guard and tackle, and the recently acquired John Moffitt, a fourth-year player who has started 15 games in his career. Moffitt is perhaps the most intriguing starting candidate. He spent 2014 away from football, but now that he's back, the former third-round pick could be a prime candidate to contribute right away.

The battle for the starting guard job will be one of the most intriguing storylines to follow come the start of Training Camp.

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2. Depth?**

Once the starting guard spots are set, overall offensive line depth will be the next pressing matter for the position group.  Between names like Kelly, Gardner, Tobin, Kevin Graf and Jared Wheeler, the Eagles have players who fit the up-tempo scheme the Eagles like to run, but that group remains largely unproven.

Gardner and Kelly filled in strongly when called upon last season, starting a combined 11 games between the two. David Molk, who can play both guard and center, also filled in nicely, starting four games while Jason Kelce missed time with an abdominal injury. A key depth player to watch heading into camp is Josh Andrews, who spent all of 2014 on the practice squad. The Oregon State product clearly caught the eye of the coaching staff as an undrafted rookie, and perhaps 2015 is the year he breaks through and makes the active roster.

Just as Andrews was brought in as an undrafted free agent in 2014, two fellow guards were signed in the same manner this season - Brett Boyko and Malcolm Bunche. Could one of these relatively unknown names earn a roster spot to provide the coveted offensive line depth? Only time will tell.

3. Could The Eagles Have The Strongest Starting Tackle Combo In The NFL?

While the first 500 words or so of this article have been devoted to the interior of the Eagles offensive line, it's also important to talk about the outside spots. Jason Peters has been everything the Eagles expected him to be when he was acquired in 2009. The seven-time Pro Bowl selection is signed through the 2018 season and has previously said that he'd like to retire as an Eagle, an idea that all fans can get on board with.

Opposite of Peters is the up-and-coming Lane Johnson, who has started 28 games in his first two seasons. A lot was expected out of Johnson after he was selected fourth overall in 2013, and he's lived up to his billing. Johnson is athletic as they come at the tackle position, and he's committed himself to working on his hand technique and footwork to break into the top level of tackles in the NFL.  

With Peters already ranking among the top tackles in the league and Johnson seemingly on his way toward the upper echelon of players at his position, it's fair to ask whether or not the Eagles possess the best starting tackle duo in the NFL. Both players are agile enough to get sweep out and flatten a defender 15 yards downfield on a run play, and both can hold their ground against the top pass rushers in the NFL. Entering their third season together under the tutelage of offensive line coach Jeff Stoutland, let's see just how great the duo can become.