Why abandon the kingdom you built?
Why leave the wing of the most powerful man in sport, Nike czar Phil Knight?
Why, indeed . . . unless he receives enough cash and enough control.
Since the Eagles' marathon dinner in the desert with Kelly nearly 2 weeks ago, assertions both insidious and ludicrous have been made about the courtship.
It was posited that, for the second straight year, Kelly dallied with the pros in an effort to secure himself more money and greater security at Oregon; last year, walking away from Tampa Bay; this year, declining Cleveland and Philadelphia.
Spurning NFL advances also served to elevate Kelly to demigod status in the great Northwest.
If so, he forsook worship for scrutiny.
It was claimed that Kelly worried that his signature "Blur" would not translate to the NFL; that Kelly had witnessed unqualified failures of such college geniuses as Steve Spurrier, whose Fun 'n Gun offense, developed at Florida, turned humorless and toothless in the NFL.
Kelly seems a bit more humble than the Old Ball Coach; no square pegs in round holes for him.
"Anything you do has to be personnel driven," he said before his Ducks won the Fiesta Bowl. "You have to adapt to the personnel you have. There's a lot of great offenses out there, but does it fit with the personnel you have? The key is making sure what you're doing is giving your people a chance to be successful."
Much will be made of Kelly's style of play, and whether it will work in the NFL.
It relies on using a flock of fast players, any of whom might gash a defense . . . except, in the NFL, the slowest defensive players make the best of the Pac-12 look like they're waddling, and there are not unlimited speedsters available on scholarship.
It relies on exposing the quarterback, ideally an athletic type who can run the ball . . . except, in the NFL, defensive linemen can often catch even the fastest quarterbacks. And once they catch them, they eat them.
Much will be made of these issues.
Little should be made of these issues.
To assume that Kelly cannot adapt is to insult the man's intelligence and his accomplishments.
Consider: A high school quarterback and a college defensive back, three of his first four coaching assignments were on the defensive side of the ball. His next four were on offense. He has been a defensive coordinator and an offensive coordinator.
He is, in a word, versatile.
He is, it appears, a lot like the best coach of the era.
Like Kelly, Bill Belichick seldom suffers fools lightly; especially ones who betray themselves with inane questions during the televised inquisitions that are modern news conferences.
Monday afternoons just got a lot more interesting, if not more informative.
Like Kelly, Belichick ignores criticisms and critiques.
Like Kelly, Belichick keeps his friends close and quiet.
It was Belichick who, after considering his personnel for 2012, sought counsel from Kelly and implemented some of Kelly's tenets . . . even though Belichick's Patriots led the AFC in yards and scoring and went to the Super Bowl the season before.
The Pats led the entire NFL in yards and scoring this season, and are heavy favorites in Sunday's AFC title game.
"I was interested to hear how he did it," Belichick told the Boston Globe. "I would say he expanded it to a different level and it was very interesting to understand what he was doing. Certainly, I've learned a lot from talking to Chip about his experiences with it and how he does it and his procedure and all that."
The double-back to hire Kelly underscores what must have been a disheartening coaching search for the Eagles.
King Jeffrey and his two princes, general manager Howie Roseman and money man Don Smolenski, beat every bush.
They passed on perceived slam-dunk candidates such as Gus Bradley, the Seahawks' vibrant defensive coordinator, and Lovie Smith, the successful and sagacious defensive savant who achieved moderate success as a head coach in Chicago.
They could not convince Notre Dame savior Brian Kelly to leave college football's most pious post, and they failed to coax Bill O'Brien from the pedestal he built for himself in State College last year.
So, they swallowed their egos, took off their hats and went back to Plan A.
It might work out.
It might implode.
Either way, Chip Kelly's latest game plan worked brilliantly . . . so far.