Shea McClellin's position on Patriots' defense among areas to watch in camp

FOXBOROUGH, Mass. -- The New England Patriots hold their first training camp practice Thursday, and here's a look at a key question/area of focus for each position on the defense (from Monday, here's the offense):

Defensive tackle: Malcom Brown, Alan Branch, Terrance Knighton, Vincent Valentine, Markus Kuhn, Anthony Johnson, Frank Kearse, Joe Vellano, Woodrow Hamilton

What to watch for: Branch has traditionally skipped voluntary workouts in the spring, which was the case in 2015, and he wasn't ready to practice on the first day of camp from a conditioning perspective last summer. If history repeats itself in 2016 after Branch also stayed away from voluntary workouts, will it open the door for Knighton to initially take Branch's starter reps?

Defensive end: Rob Ninkovich, Jabaal Sheard, Chris Long, Shea McClellin, Trey Flowers, Geneo Grissom, Rufus Johnson

What to watch for: McClellin was initially projected to be part of the linebacker mix, but he saw work exclusively at end in spring camps. Will that change? Also, Ninkovich took some linebacker reps in spring camps. Will that continue?

Linebacker: Jamie Collins, Dont'a Hightower, Jonathan Freeny, Kevin Snyder, Elandon Roberts, Ramon Humber, Brandon King, Kamu Grugier-Hill

What to watch for: Who will emerge as the third linebacker in the base defense next to Collins and Hightower, and will Grugier-Hill (sixth round, 208th overall in 2016 draft) immediately slide into a core special-teams role alongside King?

Cornerback: Malcolm Butler, Logan Ryan, Cyrus Jones, Justin Coleman, Darryl Roberts, E.J. Biggers, Jonathan Jones, V'Angelo Bentley, Cre'Von LeBlanc

What to watch for: Jones, the team's top 2016 draft pick (second round, 60th overall), could immediately slide into the No. 3 role, and then it would be a question of who emerges from the rest of the group for what could be two spots.

Safety: Devin McCourty, Patrick Chung, Duron Harmon, Jordan Richards, Nate Ebner (reserve list/U.S. rugby), Vinnie Sunseri, Brock Vereen, Cedric Thompson

What to watch for: The top four on the depth chart are locks, which means the focus turns to the back end of the depth chart for a potential roster spot, with special-teams contributions a critical determining factor.

Specialists: Ryan Allen (punter), Joe Cardona (snapper), Stephen Gostkowski (kicker)

What to watch for: All incumbents return, so this is less about the roster itself and more about how the Patriots approach changes strategically with regards to the new touchback rule.