Dwight Gooden beat the snot out of the whole league at age 19. At age 21 he threw 276 innings. Lesson learned: you can have a successful career with almost no MiLB experience, as long as you throw a sane number of innings and don't get addicted to cocaine.
Strasburg also pitched in the Olympics and had Tony Gwynn as a coach. I think if anyone could skip minor league ball, it would be Stephen.