Daryl Patton is swapping NFL allegiance from 49ers to Broncos.

The longtime Arkansas prep football coach is cheering on a fresh start for inside linebacker Dre Greenlaw. Patton coached him at Fayetteville High School during the early 2010s, and they remain in touch as Greenlaw begins a new NFL chapter.

“Every time you talk to him, when you get off the phone, you just feel better about yourself. He’s got that way,” Patton told The Denver Gazette. “We’re Broncos fans now. He’s a great, great young man.”

The Broncos and Greenlaw, on paper, are a perfect free agency fit. Denver sought to bolster the middle of its defense to match the star power of cornerback Pat Surtain and multiple elite edge rushers. Greenlaw sought a fresh start after an up-and-down 49ers’ tenure.

He led their once top-ranked defense. But the bruising 6-foot, 230-pound linebacker missed 34 games over six seasons due to several injuries; calf, groin, hamstring, quad, and a torn Achilles against the Chiefs in Super Bowl LIIIV.

Greenlaw returned last season to play in two 49ers games — just 34 total defensive snaps — after 10 months of injury rehab. Now, the big question: Will Greenlaw return to his dominant form in Denver?

“Obviously, I’m biased, but he’s my favorite guy. I think he made the 49ers better. He was kind of the heartbeat of that team,” said Patton, now the head football coach at White Hall (Arkansas) High School. “He’s going to bring high energy and a championship mentality. I think he’s gonna rub off on a lot of different players.”

Patton offers unique perspective.

Greenlaw began high school with the backdrop of a challenging home life. He entered foster care at 8 years old and was jailed at 10 for allegedly stealing a cell phone, according to the New York Post. Greenlaw overcame those obstacles to become a football star who earned a scholarship to play at the University of Arkansas.

“With his upbringing — going through foster care, and some of the heartaches he had to endure, especially in junior high and middle school days — he’s very rock hard and tough,” Patton said. “It’s hard to break him down. When adversity comes, even in high school, he was never one to sit around and say: ‘Woe is me.’ … He always came back better than before he got injured.”

Greenlaw was recruited by Arkansas as a safety but made the transition to linebacker. Vernon Hargreaves was his position coach for three seasons. Greenlaw started all four years (when healthy) and got voted team captain as a senior.

“Once he started to figure it out, you could see the athleticism start to come through,” said Hargreaves, now defensive line coach at Middle Tennessee State, in a phone interview with The Denver Gazette. “I didn’t have him his last year there, but you could see that he was growing into being a pretty good player. After he got to the league, he just started to blossom even more. You could see the confidence building in him. … From a physical standpoint, he’s always been ‘that guy.’ He’s always been pretty tough and healed up well.

“He had a broken foot when we were at Arkansas. He was able to come back from that and play really well.”

Greenlaw started 56 career games with the 49ers and was instrumental on several deep runs. He appeared in 12 postseason games, including four NFC championship matchups and two Super Bowls. Greenlaw accounted for 455 tackles (18 for loss), nine quarterback hits, three interceptions, two fumble recoveries and a pair of defensive touchdowns with the Niners.

“Dre is always positive. Dre is always; the cup is half full (rather) than empty. I’ve got a lot of confidence that he’ll be back full go. I don’t know the timeframe,” 49ers linebackers coach Johnny Holland told NBC Sports Bay Area last May. “He’s a violent, physical player. But on the other side, he’s a great teammate and we miss him being on the field.”

Greenlaw is projected to start at inside linebacker for the Broncos next season alongside Alex Singleton. The folks who know Greenlaw best are confident that he will be an impact player for years to come.

“That’s a heckuva move for Denver,” Hargreaves said. “They’re getting a good player and an even better person.”