Sometimes people say more than they intend....
I used to say it's so hard for a SB-winning QB in his careers final days to drop everything he's had so long and successfully, move across the country, start over with a completely different team and DO IT ALL AGAIN that NO ONE could ever do it
—until someone DID. Without taping practices, or play signals, or deflating any balls.
Until/unless someone ELSE does that, it's the mark to beat. Literally EVERYONE else is open to charges of "system QB" because they never did it any other way anywhere else. Not that guy: He TRANSCENDED systems.
As for Graham vs. Elway, Graham was elite, but Reeves would've loved him because he never called his own plays. And his career rushing average would make Hillman cringe. Plus two years after he retired his team was back in the NFL Championship (though they did draft Jim Brown that year, and went 5-7 the year in between.) I still think was the best PLAYER ever, because he was an elite passer, runner and even kicker. But he did it so long ago his stats are nonexistent, so it's purely a matter of opinion with only anecdotal evidence to support it.