KC has great offense, best special teams and a good but not great defense.
That said, I don't think you have to have a great defense to win. when the Rams beat the Titans, their defense was probably average. The Pats defense from a few years ago was good, but I wouldn't call it great.
Not sure you need a great coach either. Anyone remember when Barry Switzer won with the Cowboys? I don't think Brian Billick is a great coach either but he won.
All I'm saying is you don't have to have all of that, if you're good enough at some you can overcome the others.