Arnold has good genetics.........and he megadosed over a period of years.
He wasn't a hyper-responder.
DIV
On the contrary, he was a hyper-responder to drugs. The doses are a separate issue; the variance in amounts used doesn't negative the fact of being a hyper-responder to drugs. That's aside from the fact that doses weren't an exact science anyway, especially in the 60s. Schwarzenegger might well have grown on half the amounts he used; it's not as if the doses used were arrived at by any logical process.
Had most of the gains been natural, more of the size would've been retained off hormones, and the weight swings wouldn't be so drastic. He looked ok without them but the difference was disappointing, as if most of the greatness was unnatural. He looked ok off cycle, as shown in the pic.
As far as athleticism, it was his lack thereof that led him away from soccer; wasn't just an interest in individual sports. There's no sign of any particular talent there, as seen in various filmed news pieces of his lumbering gait as governor. A natural athlete in middle-age would not walk that way sans injuries.
Dillet no doubt had great genetics with or without drugs; to reduce it to drug intake's simplistic.