The only problem I have with making talent the single criterion is that many backs were more talented than Emmitt were (I guess we need to define "talent" huh?
), but I wouldn't consider them better.
As for the special designation we bestow upon Elliott, let's say he suffers a career-ending injury next year, would he be "better" than Emmitt? Would people consider him "better"? Would
YOU consider him "better" than Emmitt?
Again, my point is you can say Elliott is a special player without saying he's "better." Heck, I felt Emmitt was a special player. The only Dallas game I've seen in person was the last game of Emmitt's rookie season when he needed 63 more yards to get 1,000 and needed the Cowboys to beat the Falcons to clinch a playoff spot. Neither happened.
But I thought Emmitt was special even then. Fortunately, he went on to prove it.