How much should the throwing leg be used in the pitching motion (i.e. right handed pitcher, right leg would be the throwing leg). Do you really drive off of the mound with it hard to gain mph? I’m hearing a couple of varying stories. I know that staying “shoulder closed” as long as possible and hips on a straight line to the plate are important, but should we be focused on how hard we push off the mound?
The legs are definitely used to pitch and there is a push against the rubber. You want your stride to be as long as possible while still being able to maintain good posture and balance and getting good hip and shoulder rotation. To do this, you need to get your hips going and that requires a push with the throwing leg against the rubber. But, to me, it’s more of a subconscious push. I never tell my pitchers to “push off more” or anything like that - I only talk about their knee lift and getting their hips going.
Often, when a pitcher tries to intentionally push off the rubber, they mess up their timing.
BYW, most of your velocity is generated by the rotation of hips and shoulders - not movement down the hill.