The only thing we can be reasonably sure of is that it won't be boring. Nothing about Kelly's program, from the fastbreak offense to the ever-changing uniforms to its affiliation with Nike, is boring.
Neither was the way he made his jump to the NFL. Kelly spurned overtures from the Eagles and Cleveland Browns, announcing he would stay at Oregon. That was especially significant because the program faces possible NCAA sanctions. Kelly received applause for being honorable enough to stay and face the music.
So what does this say about his sense of honor? Eagles fans may not care today, but it is something to file away.
The more relevant question is whether Kelly's innovations can work in the NFL. There are good reasons to believe that they can. For one, the same question could have been asked when Kelly arrived at Oregon from the hinterlands. Just because an offense worked at New Hampshire, there was no reason to be sure it would work in big-time college football.
Kelly's record as head coach at Oregon is 46-7. He came within an overtime loss of playing for the national title this year. His system works.
The other positive indicator? His system, at least part of it, already is being used successfully by the New England Patriots. Bill Belichick - another guy whose entire life appears to be football - studied Kelly's offense and absorbed some of its concepts.
It surely helps to have Tom Brady running any offensive system, but there's not much chance of the Eagles' landing him.
There are serious reasons for doubt as well. Watching Oregon take Kansas State apart in the Fiesta Bowl, it was obvious that Kelly's team was dramatically quicker. There just won't be that kind of gap - in talent, in athleticism - between NFL teams.
It is one thing to ask a bunch of 19- to 22-year-old kids to practice every day at a high tempo. It is another to demand that of a roster full of 30-year-old professionals. With the recent changes in league rules, it may not even be possible.
Kelly, like every other NFL coach, will get one chance to establish his credibility and make true believers of his players. The slightest whiff of snake oil, of gadgetry, and professional athletes shut out a coach forever.
We've seen what it looks like when players don't buy in. It looks like the Eagles defense for the last two years, with Juan Castillo and Jim Washburn at cross-purposes, and Todd Bowles trying to fix the whole mess on the fly.
The defense is the other piece of this puzzle. Kelly will need a legitimate NFL strategist and leader to run his defense. If the offense is going to be a trapeze act, somebody had better be there to serve as a safety net. That is one lesson from Andy Reid's decline and fall here.
Was Kelly the best possible candidate? Time will tell, of course. There's just enough sense of the novelty act about Kelly to raise a few flags. The Eagles have made some howlingly bad decisions in recent years, congratulating themselves on their boldness right up until things blew up in their faces. Reid has taken much of the blame, but Lurie and Roseman were right there, too.
What if Kelly is just another outside-the-box, outsmart-the-world decision? Lurie could have played it safer. He could have hired an established winner such as Jon Gruden or Lovie Smith.
He didn't. He went after the highest-risk coach. Obviously, he believes that will lead to the highest reward.
Kelly is said to be very smart, keenly analytical, and fiercely determined. He'll have to be all those things, plus a little lucky, to win in the NFL.
Can he do it? We're all going to find out together.
Contact Phil Sheridan at firstname.lastname@example.org, or follow on Twitter @Sheridanscribe.