Duron Harmon’s second-year leap flew under the radar until Sunday.

Harmon has been a key contributor for the New England Patriots as the team’s No. 2 free safety, but he’d gone unnoticed until picking off Miami Dolphins quarterback Ryan Tannehill in Week 15. Harmon returned the interception 60 yards, setting up a key Patriots touchdown.

That Harmon has been invisible to the common fan is big praise for a safety, since it means he’s not giving up big plays. When the Patriots move starting free safety Devin McCourty down into the box, or when they stick two safeties deep in a Cover 2, Harmon comes onto the field.

Harmon’s strength as a deep defender has allowed Patrick Chung to play to his strengths as a strong safety. Sometimes the Patriots play with three safeties — or even four — but Chung has typically come off the field for Harmon’s 231 defensive snaps.

Dedication over the offseason has allowed Harmon to play well in his specialized role.

“Duron worked really hard in the offseason,” Belichick said Friday during a news conference. “There was hardly a day that he wasn’t in here. I’m talking about January, February, way before any of the formal stuff started. Just working out on his own, trying to improve his — get into the lifting program, just continue to train.

“(He) certainly gained a lot of experience from last year, and he’s been able to use that to catapult the start of this season. I think he understands, not that he didn’t before, just better, more experience, better understanding. He’s a really hard-working kid, smart, does a good job with the understanding, communication in the secondary, which is a big part of his position playing safety, to work with the rest of the secondary and to a certain extent the linebackers. That’s obviously way ahead of where it was last year due to his experience and probably confidence. He’s done a good job.”

The Patriots took Harmon in the third round of the 2013 NFL draft, and he displayed his versatility as a rookie, backing up McCourty and starting strong safety Steve Gregory. Harmon has 10 tackles and one interception this season, and he has been targeted only once in 185 coverage snaps.

Belichick said Harmon was one of few players around on an every-day basis right after the 2013 season concluded.

“Yeah, probably closer to five. He’s one of the most consistent guys on our team,” Belichick said. “(Linebacker Jerod) Mayo obviously is a guy that would be in that category that they’re just here. They’re working on something: they’re working on lifting or flexibility or getting some cardio in or in the training room. He worked really hard. Like I said, I don’t think the season really ever ended for him.”

McCourty has been moving down to play cornerback against tight ends recently, so Harmon’s role could increase into the playoffs.

Thumbnail photo via Steven Senne/Associated Press