In the lead-up to New England Patriots training camp, with the first public practice scheduled for July 26, it is timely to review each position on the roster with our annual “roster locks” series. After previously highlighting the running backs, wide receivers, defensive ends and linebackers, let’s move on to the defensive tackles:

Locks: Danny Shelton, Malcom Brown, Lawrence Guy, Adam Butler

On the bubble: Vincent Valentine

Long shots: John Atkins, Frank Herron

Explaining the locks: The Patriots obviously didn't trade a third-round pick in exchange for Shelton and a fifth-rounder if they didn't intend on him being a significant part of their plans this year. The 6-foot-2, 335-pound Shelton is known for his playing strength and fits the more traditional two-gapping technique the Patriots generally ask their linemen to play. So he'll be a big factor at the heart of the defense, joining Guy (6-4, 315), who made a solid first impression on the coaching staff last year with his playing strength, among other things. The 6-foot-2, 320-pound Brown is more of a tweener in the sense that he can two-gap and hold his ground at the point of attack, but can also generate some disruption as more than a power rusher when the opportunity presents itself. Butler, who made the team as an undrafted free agent out of Vanderbilt last year, is a versatile player who did some of his best work at nose tackle in pass-rushing situations as his long frame and discipline to play with good pad level showed up multiple times. He was closer to a 3-4 defensive end than a 4-3 defensive tackle last season, but is still developing and has some intriguing physical traits that bear watching in his second season.

Roster management: The Patriots usually have three big-bodied defensive tackles active on game-day, and will often rotate a third option into the game as part of not overtaxing a position that requires plenty of dirty work. That has usually meant keeping either three or four defensive tackles on the initial 53-man roster, with added depth also potentially coming on the practice squad. This was perhaps best illustrated in Super Bowl LII, when the top combination of Guy (56 snaps) and Brown (62 snaps) seemed to wear down a bit as the unit spent most of the game in its 4-2-5 nickel, and a third option was used sparingly. So developing/building defensive tackle depth that can help at any point of the 16-game season (and ideally the postseason) is generally part of the thought process when the team is constructing its roster/practice squad. Valentine, a 2016 third-round pick, spent all of last season on injured reserve (knee) and could once again be a factor. Atkins (Georgia) and Herron (LSU) are undrafted free agents who can look at the team's history (four undrafted players made the initial roster last year) to illustrate that while they are long shots, the odds aren't insurmountable.

Stat of note: Guy led all defensive tackles last season, playing 54.8 percent of the defensive snaps, followed by Brown (50.7), Butler (43.7) and since-departed Alan Branch (23.7) and Ricky Jean Francois (8.3).

One thing to watch for in camp: Once the Patriots begin practicing in full pads for the first time (July 28), it usually isn't long before the football is placed at the 2-yard line and there is a goal-line running drill, which is the first look at how the team has potentially bolstered its personnel at the heart of the line of scrimmage. That is where Shelton, who has been assigned No. 71, figures to show up most.