When the Seahawks open training camp at the end of the month, they'll do so with roster depth that "might be the best it's been," according to coach Pete Carroll. Considering the Seahawks are coming off back to back Super Bowl appearances, that's a pretty significant statement. So while players are off and we're left to count down the days until football returns, let's take a position-by-position look at that very deep 90-man roster and find out what will be at stake when the Seahawks begin camp on July 31.

Starting today, we'll preview one position group a day over the next two weeks, beginning with the offensive line.

Returning starters:

LT Russell Okung, RG J.R. Sweezy, RT Justin Britt.

Additions:

T Terry Poole (fourth-round pick), G Mark Glowinski (fourth-round pick), C Kristjan Sokoli (sixth-round pick), G Kona Schwenke (UDFA), T Jesse Davis (UDFA), G/C Will Pericak (free agent).

Key losses:

C Max Unger (traded to New Orleans), LG James Carpenter (free agency).

Last year:

Initial 53-man roster included nine offensive linemen: Okung, Carpenter, Unger, Sweezy, Britt, Jeanpierre, Bailey, Garry Gilliam and Stephen Schilling.

What's at stake in training camp:

We start this position preview with offensive line because it is the position group with the most question marks. On a team that returns most of its starters on both sides of the ball, the Seahawks lost 40 percent of their starting line having sent Max Unger to the Saints as part of the Jimmy Graham trade, and lost James Carpenter to the New York Jets in free agency.

Based on what we saw in minicamp and organized team activates, it appears Alvin Bailey is currently leading the competition to fill the vacancy at left guard, and both Carroll and offensive line coach/assistant head coach Tom Cable have praised the former undrafted free agent for losing more than 20 pounds since the end of the 2014 season. If Bailey does win that job, however, it means the Seahawks need to replace the "swing" backup role that Bailey held down the past two seasons. The realities of NFL roster restrictions means that on game day, a team can't suit up a backup for every position, so finding another lineman who can play multiple positions, something Bailey has done in the past, will be key if he does indeed end up a starter in 2015.

The battle at center, meanwhile, figures to be one of the most intriguing storylines in training camp as several players will compete to replace Unger, a Pro Bowler who has been the leader of Seattle's offensive line for several years.

Lemuel Jeanpierre and Patrick Lewis both started games at center last season, so those two seemingly have the early lead, but Drew Nowak, a member of the practice squad last season, also took a significant number of first-team reps in offseason workouts. Kristjan Sokoli, a college defensive lineman who is converting to center, has a lot of catching up to do at a new position, but he also has enough athletic upside that he can't be ruled out.

In Sokoli and the rest of Seattle's offensive line additions, it's clear the Seahawks are focusing more and more on building an athletic offensive line. When Tom Cable showed a video to fans at the Seahawks Town Hall last month, he raved about J.R. Sweezy's ability to move and block at the second level. Cable has also talked in recent interviews about measurables like broad jump, vertical leap and 40-yard dash that are critical for Seattle linemen, noting he wants linemen with "explosiveness, athleticism and a good brain." All three linemen Seattle drafted this year were among the top testers among linemen in at least one or two of those measurements.

"We're just trying to get better and better athletically, and as we do that, you still want to find those aggressive, violent athletes too," Cable said. "What's shown up is all those measurements we talked about earlier… I'd just like to get ahead of it, be a little more athletic and still as tenacious, strong-willed and tough-minded like we've been."

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