of practice. When Steve Young says he couldn't make the throws he's talking about the hs/freshman qb who had never been under center and didn't even know what a 3 step drop was, he was always the best athlete on the field, even at BYU, and he never honed in those passing skills.
But he did have the talent of accuracy, so with a lot of hard work he became a great passer. When he says you can't teach accuracy, he's talking about qb's with good/great arms who put in a ton of hard work but will never be deadly accurate.