When NFL Network did their countdown to 100 Greatest Players of All-Time several years back, he was #1. Rice set records in an era when DBs could still play some actual defense against the pass. His 10 year stretch from '86 to '95 is about as dominant for his position as any other player during such a stretch in NFL history, except maybe Jim Brown.
And just like Saban and Jordan, you dig into their performances on the biggest stage. In the NFL, that's the Super Bowl. Look at his first three SB games. His fourth was at the age of 40, and it was actually still better than what his closest challenger for best in his position (Randy Moss) accomplished in his prime SB appearance.
Every other position in the NFL there can be some debate as to who was the best (though I'd say Tom Brady may very well have closed that debate for QBs). For receiver, there's no real debate.
We may have gone away from the point of this thread...but in short, Rice is closer to the Jordan/Saban level of his trade than Brees is to him. And Rice had that same obsessive compulsive trait as those two.