DURHAM, N.H. -- The University of New Hampshire football offices are on the bottom floor of an old, bunker-like building called the Field House. The carpet is drab. The lights sometimes flicker off. The walls are concrete, like a dungeon. On game day, coaches have to climb two ladders and scale a catwalk to get to their box, an American Ninja Warrior course navigated by men wearing headsets, pleated pants and a smile full of dip.

All in all, it's one of Chip Kelly's favorite places.

UNH is more than where Kelly played quarterback and defensive back, earned his degree, began his coaching career and conceived a football system from which the likes of Bill Belichick would later borrow. It's where Kelly left something of a vapor trail, the remaining aura of a time and place that can never be recreated. You notice it as you walk past team pictures from 1994 to 2006 and see his unsmiling face buried among anonymous assistants. You see it in the equipment room, where there's a story behind the Oregon Ducks helmet hanging on the wall.

After Kelly left for Eugene in 2007, the UO equipment guys called with a conundrum: Kelly refused to wear Ducks gear at the gym, instead sporting a ratty UNH sweatshirt. So they asked for a box of UNH stuff in exchange for Oregon gear. Problem was UNH didn't have extras, so a few staffers bought Kelly some sweatshirts from the school bookstore. They later heard that Kelly still wore his old one.

But you feel Kelly's ghost most in the small office of Sean McDonnell, the Wildcats' longtime head coach. He is Kelly's former boss and one of his best friends. He has white hair, an easy smile and a scratchy voice that has paid the price for his Irish temper. "Mac" has a stellar résumé -- leading UNH to the FCS playoffs nine straight years, the longest streak in the nation -- and he is secure enough to indulge all of the national media outlets that visit solely to ask about Kelly.

Mac remembers Kelly being a "sponge" who "wanted to absorb everything about football and teaching" but who was "never afraid to change." In 1999, Mac promoted Kelly to offensive coordinator after he spent three seasons coaching running backs and two tutoring the offensive line. Kelly visited other college and pro teams each offseason, and the culmination of those trips produced a system of football that is lore only in retrospect.

The pace was so dizzying that the Wildcats made the ordinary no-huddle look slow. Kelly did it all with one simple goal in mind: score more points than anyone in the country.

Within years, many NFL and major college teams would adopt Kelly's philosophies. But in the beginning, Mac was not such an easy sell. The Wildcats were losing. Jobs were on the line. Mac was afraid Kelly's hurry-up offense would hurt his defense.

Kelly's solution? Stop punting. "We'll score 60 points," Kelly would say. He loved trick plays, which just increased Mac's blood pressure. Kelly once practiced a dolled-up version of the hook-and-ladder that Mac nixed with a simple glare. In meetings Kelly would design an inside zone running play in which receivers would sprint off and extra linemen would hustle on, all in hurry-up. "I'm telling you, Mac," Kelly said, "they won't be ready for it. Go no-huddle, boom."

Kelly proved he could win with any kind of quarterback at New Hampshire, a quality that would serve him well as he tutored Nick Foles in 2013. AP Photo/Philadelphia Inquirer/Ron Cortes

"Come on," Mac said.

"Mac, they won't have any idea."

The thing was, Kelly was right. By 2002, his offense was unstoppable. That year Kelly seamlessly switched midseason from a running quarterback to a passing one -- an adaptability that would be refined at Oregon and mastered in Philadelphia. Kelly's offense would eventually produce 80 offensive plays a game, set school records and become an underground phenomenon in coaching circles. Kelly seemed to derive as much joy from exhausting opponents as he did from scoring touchdowns. "Look at 'em, Mac!" he'd say, as defenders struggled to pull themselves off the ground.

During New Hampshire's practices, it was as if two different sports were being played. On one side of the field was the defense in full pads, pausing for instruction between plays -- same as always. On the other side the offense was in sweats, sprinting between snaps. What motivated Kelly was a mystery to Mac. Unlike most coaches, he wasn't chasing the next job. He once sat in Mac's office as his boss lamented all the administrative issues on his plate and said, "I never want to be a head coach." (Years later, after his Oregon debut was marred by a loss to Boise State and star running back LeGarrette Blount punching an opposing player, Kelly called Mac and said, "This is why I wanted to be a head coach.")

Still, UNH staffers don't talk about Kelly with any mythical reverence. To them, he was just "Chipper" or "Charlie." He was so important that he warranted a designated seat on the team bus but so indifferent that he didn't care if someone else sat in it. When he called a bad play or recruited an underachieving player, he'd say, "I blew it." He taught Mac more about how to have fun than about the read-option. Once, before a trip to the Bay Area for a game against UC-Davis, Kelly asked Mac, renown around the office for being uptight, to let the team walk the Golden Gate Bridge.

"Really, Chip?"

"Mac, it'll be unbelievable. Just trust me."

Mac begrudgingly allowed it. Days later the team bus pulled up to the bridge. Mac, a lifelong Northeasterner, expected it to be short, "like a football field." Nope. He glared at Kelly, who pretended to ignore him. Hours later, the players and coaches finished. After the bus drove away, someone realized that they had left the school's biggest booster behind. Mac stared at Kelly again, and this time Kelly couldn't feign ignorance. "Almost perfect," Kelly said.

On a July morning in his office, Mac looks at a framed picture of the team from that day. He smiles. Seems like yesterday. Mac has visited Eagles practice the last two springs. Kelly has a house on the New Hampshire coast and returns to campus a few times a year -- sometimes to speak to the team but mostly to shoot the bull with old friends. The years have flown by as fast as a Kelly drive. In a quiet moment, Mac ponders what he knows about Kelly now that he didn't know back then.

"I didn't know how smart he was," he says.