3. HE SPINS HORSE CRAP INTO TOUCHDOWNS

Kelly first thought of it on a field that, when the wind blows, smells like shit. Seriously. The football field at the University of New Hampshire is across the street from a horse stable. In 1999, as a mid-30s offensive coordinator, he sat in head coach Sean McDonnell's office and asked, "Why can't we be the best offense in the country?"

Now, it's almost unheard of for a young coach to be so transparently ambitious -- not to mention at a Division I-AA doormat. But Kelly has always defined his career on the traits that defined his childhood, when he was a self-described pain in the ass who questioned everything. At New Hampshire, Kelly spent vacations visiting other college programs and NFL teams. Trips to Northwestern and Clemson, both of which operated the hurry-up, produced a revelation of sorts: The more plays he could run, the better chance he would have to score.

Of course, there have been many iterations of the hurry-up. But Kelly was the first to explicitly make the volume of plays as important as their execution. It meant deploying every advantage -- motion and misdirection and making simple plays appear complicated -- and sometimes spending as little as five seconds between when the ball was set and when it was snapped. It meant treating fourth down as if it were first. It meant taking over the kick-return unit because, as he said, "it's the first offensive play." It meant practicing at a lightning pace and aiming for 80 plays a game, 23 percent more than most teams, and trashing tired metrics like time of possession in favor of smarter ones like points per possession. It meant only one goal for his offense, always printed on the first page of Kelly's playbooks: SCORE POINTS.

Finally, it meant basing an offense on the idea of no limits when so many coaches do the opposite. As Mike Belotti, Kelly's former boss at Oregon, says, "Instead of why, he says why not."

By 2002, Kelly knew he was onto something. His offenses would break 29 school records in 2004 and average 41.7 points per game a year later. At Oregon, first as offensive coordinator in 2007 and then as head coach in 2009, Kelly explored sports science, fusing innovation to schematics. Pro teams began to consult with and borrow from him. In many ways, Chip Kelly was the NFL's future before he was even in the NFL.

He arrived in Philadelphia with an offense recognized as much for its unorthodoxy as for its speed. It didn't rely on audibles. It didn't concede that the best way to score is by throwing. And it didn't require a 700-page playbook. As Kelly once said: "Instead of trying to outscheme your opponent, put your players in an environment where they can be successful because they understand exactly what they have to do."

Ricky Santos, who played quarterback at New Hampshire under Kelly and now coaches receivers there, watched the Eagles early last season and saw traces of the packaged plays Kelly ran at New Hampshire. One call against the Broncos began with Vick turning to hand off to McCoy on a bread-and-butter zone run. But Vick kept the ball. Now it appeared to be a read-option, which put the linebackers in "dual conflict," as Kelly likes to say. Vick then glanced left to throw a bubble screen, another Eagles staple. But as Denver's secondary flooded that way, Vick fired to tight end Brent Celek, who was left wide open on a post route by a defense overextended by four basic concepts. The play went against the Eagles' tendencies twice and set up McCoy to find space on the simple zone run three snaps later.

Santos says he wrestles with the confounding mystery familiar to most coaches who have studied Kelly: He knows what Kelly is doing -- yet he still wonders how he does it. At dinner one night this past spring, when Santos asked his former coach for insight, Kelly replied simply, "It's just football. Whatever level, it's just football."

4. THE TRUTH SETS HIM FREE

By Week 6 of last year, the NFL's future sure doesn't look like it. Philadelphia is 2-3 and about to play Tampa Bay. It's a weird time to be an Eagle. Players used to party in Atlantic City after games. Not now, with the boss tracking sleep. Saturdays used to be light walk-throughs. Not now, with the boss having learned from Olympic runners that the best way to maximize performance is to run hard the day before the race. At the end of each week, Kelly brings in an expert to explain his methodology, but it's not fully connecting. "Keep doing the small things," Kelly tells the team. "I promise we're going to where we want to be."

Worse, teams seem to be finding answers for Kelly's offense. In September, Reid's Chiefs force five turnovers and hold Philly to 16 points. A week later, the Broncos out-hurry-up the Eagles and win by 32. Against the Giants the next week, McCoy is held to 2.3 yards a carry, and Vick pulls his hamstring. Nick Foles, who had eight turnovers in seven games in 2012 as a rookie, is now the starter.

When McCoy struggles, he tends to dance in the backfield. Nothing angers Kelly like throttled speed, and it boils to the surface against the Bucs on Oct. 13 when McCoy is slow to an opening.

On the sideline, Kelly unloads: "Hit the damn hole, Shady!"

"There was no damn hole!"

"Shut up!"

McCoy heads to the bench. But he can't let it go. He brings Kelly a photo of the play and says, "Do you see a hole?"

Kelly returns to the game, and McCoy returns to wondering whether he can coexist with his coach.

But in the team meeting the next day, Kelly says something the players have never heard so explicitly from a head coach: "Shady and I got into it, and I was wrong."

5. HE IS HAS A HARD ASS

At an afternoon practice, McCoy slaps Kelly's ass, just to mess with him. Later, Kelly approaches him, looking serious. Now, in instances like this, you never know what Kelly might say. Once, after a goal-line fumble by Santos, his quarterback at UNH, Kelly put a comforting arm around him and said, "Congratulations for single-handedly losing us the game." A couple of years later, when Santos came to the sideline in the tense fourth quarter of a playoff game, Kelly said, "What commercial do you think is on right now? I bet it's that Peyton Manning commercial -- 'Cut that meat!'" Santos laughed and then threw the game-winning touchdown.

This time, Kelly says to Shady, "Did you get hurt?"

McCoy is confused. Hamstring? Knees? Shoulder? Nope, all good. "Hurt?" he says.

"Your hand! This thing's tight."