Devin McCourty is one of the best free safeties in the NFL. He is rangy and smart, a leader in the locker room. He hardly misses any snaps and allows the Patriots to use aggressive coverage schemes even after Darrelle Revis and Brandon Browner have left town.

Duron Harmon is no Devin McCourty.

Still, Harmon is a valuable member of the Patriots secondary in that he displays similiar abilities to McCourty's and thus allows the team to use its star free safety in more ways than just as a deep centerfielder. New England's coaching staff likes to move McCourty around – and Duron Harmon allows them to do that.

Let's take a look at three plays from the Patriots' 36-7 victory over the Miami Dolphins last Thursday, to find out how Harmon is used by the team – and how it allows them to use other parts of their secondary.

1) 3-10-MIA 6 (12:07) (Shotgun) 17-R.Tannehill pass incomplete short left to 18-R.Matthews [50-R.Ninkovich].

Down 9-0 in the early second quarter, the Dolphins face a 3rd-and-10 situation near their own goal line. It is a obvious passing down and New England therefore counters Miami's 11 personnel with three down linemen, two linebackers and six defensive backs. When running back Damien Williams moves from the backfield to the right side of the formation, Devin McCourty moves closer towards the line of scrimmage from his original spot in the two-deep safety alignment:

The Patriots can make this move because they trust Harmon to be the lone center field player – he has the vision and range to do that. At the snap, the linemen and linebackers all rush, while the defensive backs play close man-to-man coverage. Harmon's role in this cover 1 concept is to prevent anything from going deep:

The Patriots play the down perfectly: Chandler Jones and Rob Ninkovich pressure Dolphins quarterback Ryan Tannehill into making a quick throw towards Rishard Matthews. The wide receiver was unable to gain any separation from cornerback Logan Ryan and the ball falls incomplete. Miami is forced to punt.

The first play illustrates how the coaching staff trusts Harmon to carry out his assignment and play as a deep safety. This consequently allows fellow safety McCourty to be moved around depending on the formation the opposing offense shows. The following play now shows that Harmon is able to answer the call and deliver as the deep safety when he or his area is targeted.

2) 2-7-MIA 26 (14:31) (Shotgun) 17-R.Tannehill pass deep left intended for 10-K.Stills INTERCEPTED by 30-D.Harmon at MIA 45. 30-D.Harmon to MIA 15 for 30 yards (17-R.Tannehill).

Early in the fourth quarter, with the Patriots up 22-7, the Dolphins needed some offensive spark to come back into the game. The team comes out in its usual 11 personnel formation with running Lamar Miller in the backfield next to Tannehill and tight end Jordan Cameron close to the formation next to the right tackle.

The Patriots once again use six defensive backs. They show man-to-man coverage when wide receiver Kenny Stills moves further inside prior to the snap but actually employ a cover 2 zone defense with McCourty and Harmon as the two deep safeties and Patrick Chung as a safety-linebacker-hybrid, covering the underneath middle of the field:

Harmon being responsible for the right side of the defensive field shows great anticipation and vision sliding over from his safety spot to make a leaping interception off a pass intended for Stills, whose route ended in a collision with cornerback Justin Coleman:

Having the former Scarlet Knight as a safety, who is able to cover the deep portion of the field alongside McCourty, also allows the team to use another one of its safeties – Chung – in a role perfect for his particular skill set: closer to the line of scrimmage and as a defender of runs/running backs and tight ends. On both plays we have looked at thus far, Chung basically is used as a linebacker.

3) 1-10-NE 28 (5:15) (No Huddle, Shotgun) 17-R.Tannehill pass incomplete deep left to 14-J.Landry [54-D.Hightower].

Late in the game and down multiple scores, Miami became one-dimensional and abandoned the run. Therefore, New England had to stay in its multiple defensive backs formations. On a 1st-and-10 on their own 28 yard line, the Patriots once again played man-to-man coverage and used Harmon as the lone deep safety. This time, McCourty was used to cover Cameron, aligning in the left side slot, while rookie Jordan Richards was responsible for the intermediate middle of the field and Tannehill's check-down player, Lamar Miller.

Just like he did earlier in the fourth quarter, Harmon displayed great vision, reading the quarterback's eyes perfectly to slide from his position to help Malcolm Butler break up the pass intended for wide receiver Jarvis Landry:

This game of course did not mark the first time the three-year veteran Harmon was used as a deep safety; he also played this role in last year's playoff run, for example. Still, given the fact that the Patriots' secondary underwent a drastic personnel change from last year to this season, Harmon and his impact need to be pointed out.

His play gave the coaching staff confidence to regularly use him as a deep safety, which in turn allowed McCourty and Chung to move around. This helps address potential coverage mismatches or mask deficits due to the relatively young and thin cornerbacks corps.

Seven games into the season, the secondary performs admirably – better than most probably anticipated. Duron Harmon and his impact on the safeties' usage is a big yet underrated reason why.