By Matt Dolloff, 985TheSportsHub.com

Dont'a Hightower has long blossomed into one of the NFL's better defensive captains, the engine of the New England Patriots defense, and a proven big-game performer when the lights are their brightest. He has the versatility to rush the passer, play on the edge, and man the middle of the unit. And he's an effective play-caller, no matter where he lines up.

When he's on the field.

Unfortunately, Hightower plays one of the most physically demanding positions in sports and has struggled with his durability throughout his career. His latest recovery is from a torn pectoral muscle suffered in Week 7 of the 2017 season, after already missing two games earlier on. The injury left the Pats without a true No. 1 linebacker, or any player who can even come close to replicating his skill set, for the remainder of 2017.

They also missed Hightower's innate clutch ability when they failed to come up with a big play late in Super Bowl LII against the Philadelphia Eagles. Up and down the field Nick Foles and Philly went, all night, with barely a hint of resistance from the linebackers or any level of the Patriots defense. The secondary had an ugly night without Malcolm Butler at its disposal, but so did the linebackers when forced into coverage. Besides the now-departed James Harrison, they couldn't generate any pressure on Foles from that position, either.

Hightower has missed at least three regular season games for the past four seasons in a row. If and when he once again has to miss time in 2018, it's going to be on those same players to be better than they were last year. It's a fair question whether they'll be capable of improvement, and the biggest question facing the defense entering the season.

Meanwhile, in Foxboro...

Other areas of the defense enter training camp with reinforcements from free agency or the upper half of the draft. At linebacker, the only pieces added are from the fifth round or later in 2018. There's always the chance they get the internal improvement they need out of the rookies, but if this group loses Hightower and again has to lean heavily on Kyle Van Noy, Elandon Roberts, and Marquis Flowers ... there's a good chance that the ripple effect of losing Hightower will be felt as strongly as it was in 2017.

During mandatory minicamp in June, the Pats mostly lined up the same three linebackers in their main defensive drills: Hightower, Van Noy, and Roberts. Rookie fifth-round pick Ja'Whaun Bentley got some occasional reps. Fellow rookie Christian Sam has the most potential of the younger Patriots 'backers to make an impact in the areas where the positional group needs to improve, but spent most of minicamp away from the main team drills.

Camp Previews: RB | WR | TE

Bentley is bigger and more physical than Roberts, but has a chance to play a similar role. The rookie should push Roberts for snaps, if not a roster spot, in most situations against the run. Sam will have an opportunity to earn a role against the pass and play on special teams, and represents the most promising new addition in terms of a coverage linebacker.

Flowers has likely cemented a roster spot as a core special teamer after signing a one-year extension with the Patriots for up to $2.55 million. The question is how much defense he will play in 2018. He played well in the AFC Divisional Playoff against the Tennessee Titans, but got burned for a crucial 22-yard touchdown to Eagles running back Corey Clement in Super Bowl LII. If Sam doesn't contribute quickly, Belichick and Brian Flores will depend on Flowers just as much in coverage, if not more. A strong training camp for Flowers would be telling as far as the direction the defense will take.

At the bottom of the depth chart, 2017 undrafted free agent Harvey Langi remains a dark horse to earn a roster spot after some unfortunate setbacks in is rookie year. Brandon King is listed as a linebacker on the Patriots' website and will likely maintain a key role on special teams, while Nicholas Grigsby will again compete for a spot on that unit.

Camp Predictions

Hightower and Van Noy are the only locks to make the roster if they're not traded, but Bentley and Sam should be able to survive their first training camps and put pressure on Roberts. Provided those rookies do show promise, Roberts could end up on the bubble with other linebackers nailing down roles on special teams. ... Flowers and King will almost certainly make the team as key parts of the Pats' elite special teams units. ... Langi and/or Grigsby will end up cut, or possibly even moved to the practice squad. Langi could ultimately earn a spot with his potential as a pass-rushing option.

Overall, the group will improve considerably upon the end of last season with Hightower back in the lineup. But, if and when Hightower is out, the same questions mostly remain as to how well they could hold it together. The rookies will have good chances to make a real impact, but they can't be relied upon nearly as much as Hightower usually is. With no major reinforcements coming in this offseason, this is once again a position that will depend greatly on its captain.

Matt Dolloff is a digital producer for 985TheSportsHub.com. Any opinions expressed do not necessarily reflect those of 98.5 The Sports Hub, Beasley Media Group, or any subsidiaries. Have a news tip, question, or comment for Matt? Follow him on Twitter @mattdolloff or email him at [email protected].