As we often do, when we’re casting, you cast for the immediate role at hand — which was Sam Wilson in Captain America: The Winter Soldier, but if it all goes well, that can grow and evolve into numerous things.
The first experience was him being the unanimous first choice to play the character.
We just offered him the role, in my memory; he did not audition.
You want an actor who can do it all, which of course, Anthony can.