Is the Mike Smith mentioned by Sam the same Mike Smith who is now the head coach at Ole Miss? Just wondering.
I tend to think it's some combination of both as far as born vs made with emphasis on the made side. A lousy pitching coach can ruin even the best bred pitchers. My kids started getting private pitching lessons from a former men's fp player, Jim Brackin, who retired early in my oldest dd's HS career so my youngest started around 12u with Denny Tincher. I'm still glad we worked with Brackin when we did because he was very good at pitching instruction compared to anyone else nearby and fairly accessible but as someone who was known mainly as a hitting instructor he didn't have the eye for detail that Tincher does. The other thing I now realize in hindsight is that it isn't necessary to go to pitching lessons every week, we only saw Tincher somewhere between 3-5 times per year.
On the "born" side, both my kids were very much on the stoic side mentally. When I see a young pitcher fighting off tears in the circle or glowering at a teammate who made an error or an umpire who's squeezing them I tend to think they don't have it between the ears to be pitchers.