Linebacker depth Jaguars' top concern entering training camp

The Jaguars hope Myles Jack can take charge as the middle linebacker and on-field communicator for the defense this season. David Rosenblum/Icon Sportswire

The Jacksonville Jaguars open training camp on July 26 at the Dream Finders Homes Practice Complex. Here's a closer look at the Jaguars' camp:

Top storyline: Myles Jack moves to middle linebacker full-time, and the hope is the transition goes smoothly. The team tried to move him there last season, but he struggled and defensive coordinator Todd Wash eventually moved Paul Posluszny from strongside linebacker back into the middle on first and second downs. Jack spent a lot of time during organized team activities and minicamp working on coverages and drops while he rehabbed a hand injury. Weakside linebacker Telvin Smith is one of the defense's best playmakers, but there's a void at strongside linebacker. Blair Brown and Donald Payne got a lot of reps there in the spring, but neither has an edge on the other. The depth is a huge question mark as well. The Jaguars need a couple of reliable players to emerge as solid special-teams players and guys who can start in a pinch because of injuries.

QB depth chart: Blake Bortles signed a three-year, $54 million contract extension through the 2020 season after he put together the best season of his pro career in 2017. Bortles had the best OTAs/minicamp of his career this past spring, too. Unlike last year, there are no questions about his status and whether the team believes in him. Cody Kessler, for whom the team traded in March, is the clear No. 2. Sixth-round pick Tanner Lee is likely headed for the practice squad.

Bubble watch: The roster is pretty much settled and there isn't a notable veteran who is in danger of not making the squad. Right tackle Jermey Parnell is really the only notable veteran who could lose his starting job, mainly because he turns 32 in July and the fact the team drafted his eventual replacement. However, Parnell has played well the past two seasons when he wasn't bothered by an injury and is a big reason the Jaguars have cut their sack totals in each of the past two seasons (34 and 24, respectively). However, the Jaguars drafted offensive tackle Will Richardson in the fourth round in April. Richardson worked with the second and third teams behind Parnell throughout OTAs and it doesn't appear the Jaguars are going to give him a lot of first-team reps (if any). Parnell should be the starter in 2018, but that could change if he gets hurt or Richardson has a monster camp.

This rookie could start: Hard to see any rookie earning a starting job without an injury (even Richardson is unlikely), but the one with the best chance would be receiver DJ Chark. The second-round pick from LSU impressed teammates with how quickly he seemed to pick up the offense, his smooth route running and his hands. The 6-foot-4 Chark made perhaps the most impressive catch of OTAs/minicamp when he jumped to snag a pass and managed to get the toes of both feet in before falling out of bounds. Marqise Lee, Donte Moncrief and Keelan Cole are the Jaguars' top three receivers, but if Chark continues to impress he should get significant playing time and could possibly end up a starter before the season ends.

Testing the receivers: The Jaguars will have joint practices with Minnesota on Aug. 15-16 at Minnesota State University, Mankato. It's going to be a very good test for the offense, because the Vikings' defense led the NFL in yards allowed, scoring, third-down conversions and also gave up the fewest TD passes last season. The Jaguars' receivers will be tested by two of the league's best defensive backs -- cornerback Xavier Rhodes and safety Harrison Smith -- and Jaguars coach Doug Marrone can come away feeling pretty good about that group if it holds its own. Outside of Lee and possibly Moncrief, the receivers still have a lot to prove.

Tough days ahead: Expect a mentally and physically grueling camp in Year 2 under Tom Coughlin and Marrone. That's what happened last year -- at one point the players went 15 consecutive days in full pads -- as Marrone and Coughlin tried to change the culture. It clearly worked: the Jaguars were the league's biggest surprise in 2017, going 10-6, winning the AFC South and coming within 10 minutes of reaching the Super Bowl for the first time in franchise history. Marrone has talked often about re-establishing the foundation every year, so it's going to be another tough month.

For daily updates at camp, check out the Jacksonville Jaguars clubhouse page.