Two things I've noticed when scouting pitchers is stride length and drag are very important. Stride length is pretty obvious, but a thing a lot of people don't know about is drag. Drag is how much your foot has dragged from the rubber when you're throwing the ball. Look at a video of Greg Maddux pitching and you'll see his foot when he releases the ball has dragged a lot. If he does this, he's releasing the ball closer to the plate, what I've noticed is it can make up for a difference of maybe 3-5 MPH. Also, if a pitcher's release point is closer to the plate, he can gain a lot of velocity. I remember Trackman showed velocity adjusting for release point, and the numbers were much different. I remember when watching Joba Chamberlain pitch, his fastball velocity was overrated because he had almost no drag, so he was releasing the ball farther away from the plate, and his stride was short, so he was also releasing the ball farther from the plate that way too. From my experience as a pitcher, having a shorter stride length also means less control. It's harder to control when your stride is short. Watch Roy Halladay or Greg Maddux pitch, and you can see that these two things can result in a big change in velocity. When I've seen Manny Banuelos pitch, his stride is short and he has no drag. Someone like Brett Marshall has a very good drag and his stride is pretty long too. Though Banuelos throws a bit harder, I think Marshall is actually getting the ball to the plate quicker.
I've seen a lot of pitching prospect busts with a short stride length and no drag, and a release point not that close to the plate. I already mentioned Joba, but Homer Bailey is another one. I think a reason is that a pitcher's velocity can get overrated.
Has anyone else noticed important things in scouting like this?