when was the last time a college coach came to the NFL and had success? not saying they won't but minimally it will take them sometime to learn the ways of the NFL. these college coaches run the spread offense with multiple WRs and bet that the college defenses, specially the defenses 2rd, 4th and 5th DBs aren't as good as their WRs...that's why you see so many athletic, fast players play WR. the defenses in college are less sophisticated, with less athletic players, and the offenses can take advantage that you may stop me once, maybe twice, but routinely I am going to find holes in your defense....I bet that my 4th WR is better than your 4th DB....
in the NFL, its the best of the best, defenses are sophisticated, everyone is athletic and the schemes from college don't necessarily work in NFL> its made its way, but there is a lot of element from traditional NFL schemes mixed in there to make it work.
and I always argue that its not the scheme, scheme ain't going to get anybody open or shut them down. its how you call plays on game day, how you mix up the personnel and routes. how you do pre-snap movements, etc. we don't know if Riley can do any of those at the NFL level. Kelly came from Oregon with a lot of fanfare. he was going to revolutionize the NFL...well, it didn't work out so well.
I am not sold on riley, unless like AZ, you have a craapy team, rebuilding and can give time to your coach to learn....we have a superbowl ready team....wasting a few years for Riley to learn...we waste the best years of our players....
there are other hot, good NFL assistants, ready to make the leap.....