So is a person in the strong man competition considered athletic by your standards?
I know you're not referring to me but athletes who try the crossover from another sport to football usually fail miserably for several reasons.
1) They're not used to the complexity of the game (i.e. playbooks, situations on the field, studying film on opponents)
2) The type of condtioning you need in football is different than they type of conditioning you would need in most other sports.
3) Most who tried weren't used to the physical beating they'd take, except for Brock Lesnar who tried for the Vikings.
4) The sports skills themselves are completely different. A 500 pound bench press won't do **** for you if you can't recognize a blitz, get off the ball like a bat out of hell, and know all the proper techniques you will need for your opponent.
The only guy who I remember making the transition from another sport to football was James Jett of the Raiders. He had 3 decent seasons as a starter and about another 5 as a 3rd receiver. He was an Olympic sprinter before hacking it with the Raiders. Bo and Deion don't count either because they had experience in college and high school before turning pro at 2 sports (that still boggles my mind)