I wouldn't call what I do for NFL a system. I just look at the teams' records, home and away. Look back over who they have played and how that went (with some general idea of those opponents strength) - come up with an impression and see how it compares to the spread and total. ---> that's about it.
I wasn't lyin' about it being my easiest sport. Compared to what I did for baseball and other sports --- it was a walk in the park.
As unimportant as posting picks on forums has always been to me, NFL capping success is the one thing I actually have some internet proof of. I know I am in the top few all-time for the Beat The Prick contest. Someone posted those standings here awhile back. I guess they are available somewhere. That would have been based on hundreds of NFL picks over 5 years or so - and doesn't even include the time I did picks for my friend Tom and finished 1st overall and won the Harley.
Lots of people do say they find the NFL difficult (but then again most people lose long term at everything.) Whatever, I seemed to have a feel for it which went back for decades.