John Moffitt mystery clouds line picture

PHILADELPHIA -- NFL teams are reporting to training camp this week. The Philadelphia Eagles, who will hit the field at the NovaCare Complex on Sunday are one of the last teams to start camp.

When they do, there will be a quarterback competition as well as a slew of new defensive players to watch come together. This week, as we count down to the start of camp, we'll take a look at some of the less obvious issues that will be addressed this summer. Today: a look at the offensive line.

In June, after all the organized team activities and minicamp practices were over, the Eagles signed offensive lineman John Moffitt. Moffitt, 28, had abruptly retired early in the 2013 season. He has since been arrested and gone through treatment for substance abuse issues.

The big question: Did coach Chip Kelly bring Moffitt in as an extra candidate for one of the two open jobs on his offensive line? Or did Kelly sign Moffitt because none of the other candidates were showing enough promise? In other words, did Kelly learn from OTAs that he needed someone else to play guard?

The Moffitt mystery is connected to another mystery. Why did Kelly, after two seasons, decide to jettison a couple of pretty solid offensive guards named Evan Mathis and Todd Herremans? They were both scheduled to make about $5 million this season, which is a lot for a guard. To make things even more difficult, Mathis found his $5.5 million salary low enough to inspire him to skip all of the team's voluntary workouts.

That couldn't have pleased Kelly, but coaches tolerate that sort of low-level insubordination all the time. After all, Mathis was merely following the letter of the collective bargaining agreement. He would have reported for the mandatory minicamp if Kelly hadn't released him a few days before it started.

The message seems to be that Kelly doesn't think guards are nearly as important, in the scheme of things, as tackles and centers. Left tackle Jason Peters' $9.05 million salary-cap charge for 2015 wasn't a problem. The numbers for Herremans and Mathis were.

But we saw how inconsistent the Eagles' offensive line was in 2014 with a lack of continuity in the guard play. Mathis injured his knee in the first game of the season and missed the next seven games. Herremans tore his biceps and missed the final eight games.

Dennis Kelly started two games at left guard and one game at right guard. Andrew Gardner started six games at right guard. Matt Tobin started five games at left guard and two at right guard.

Those three players were the top candidates for the right guard job during OTAs and minicamp. It is important to note the coaches opted to replace all three at some point in the 2014 season. Gardner was replaced at right tackle by Herremans, Dennis Kelly was replaced by Tobin and Tobin was replaced by Gardner.

With Allen Barbre slated to start at left guard, the Eagles were counting on one of those three to take the right guard spot. The addition of Moffitt means that four players are competing for the job.

It will be interesting to see how the offensive line looks on the very first day of camp. Two years ago, Kelly had rookie Lane Johnson line up with the first team from the very beginning of camp. Last year, with Johnson facing a suspension for the first four games, Barbre took all the first-team reps at right tackle.

In other words, Kelly likes to have his offensive lineman play together as much as possible. So he will likely have the player he wants, or expects, to win the right guard spot line up there early in camp.

There will be some other subplots. Can rookie Mike Coccia challenge David Molk and Julian Vandervelde for the backup center spot? Will the ability to play guard in a pinch be the difference in the backup center picture?

And will Gardner be in the right guard competition or will Kelly have him focus on being the backup at both tackle spots? Will someone else -- Dennis Kelly? Kevin Graf? Rookie Brett Boyko? -- emerge as the backup tackle?

The answers will start to come as camp gets underway next week.