That's because it's changeable. You can learn these new tricks and discover hidden skills. It can often alter a career by several degrees. Some pitchers excel using only the fastball. Rare pitchers can compete only with their dexterity and control.
Nobody succeeds without knowing the science.
That's why I mistrust young pitchers. Young guys are dumb. Their talent is measured by a single standard, which is constantly declining. That's the trick. Unfortunately, any significant statistical measure of pitching skill is polluted heavily by context and sheer luck - saves, wins, Losses, earned runs, hits allowed, homeruns, strikeouts and walks.