Getting confused

With a sinker,screwball,and a running 2-seamer you need to pronate. But what makes this pitches different from each other because you grip a screwball and a sinker the same way. The running 2-seamer has the same motion as a screwball and a sinker. What makes this pitches different?

its the extent and timing of the pronation. you pronate even on a four seamer but its after release. the longer you keep your fingers behind the ball the faster the pitch will go but it will most likely have less movement. a screwball you pronate hard at release. this reduces the amout of time the force is applied to the ball thus it goes slower but by pronating hard at release it puts tremendous sidespin on the ball causing it to break much more than a two seamer. the running two seamer i believe is more a product of arm angle than pronation. your fingers stay behind the ball almost as long as a 4 seamer but with the lower arm angle the axis of the spin is tilted, as well, causing the ball to move more laterally.

wow that actually makes sense thank you

With a screwball release, your hand and fingers are on the extreme inside of the baseball. The release is the exact opposite of a curveball, where your hand and fingers are on the extreme outside of the baseball. A “perfectly” thrown screwball from a righty will have lefty curveball spin.

With a sinker, your fingers are a little behind the the ball still at release. This explains why some guys can throw sinkers in the low-mid 90’s (Carmona, Hernandez). It’s just an off-center fastball. A perfectly thrown sinker will have opposite arm cutter spin.