Thought about this some more today while offline: I guess I will advise my son to give a little thought/effort to a wind up, so that if a college coach is pro-windup, then Chico Jr. can honestly say “I have worked some on that, but I still feel more comfortable from the stretch.”
Since most starting Ps usually practice primarily from a windup (at least in my experience), I would expect many of them throw harder that way because it is more familiar. And vice versa for relief Ps. But I still think that even the old school guys don’t *really* believe a wind up is inherently better, despite what they say. Don’t just about all MLB relievers pitch from the stretch even with no runners on? If MLB PCs truly believe a wind up is good for an extra mph or three or will deceive batters by hiding the ball, wouldn’t they insist relievers use it? Maybe some relief Ps couldn’t learn to be effective from the wind up, but would teams (or players) really leave any extra velo on the table if it’s there for them? I’m trying to imagine Mel Stottylmeyer telling Mariano Rivera, “Mo, you look pretty good out there, but let’s try a wind up.” Not even when Rivera was a set-up man and only an aspiring closer.
It also occurs to me that when my son pitches with no runners on, he lifts his front foot about waist high. With runners on, he uses a slide step. So in effect, he’s using a sort of half-windup. And I have never checked, but I expect he throws harder with the leg lift. Which is contrary to my thesis that there is no difference...
This is why I stopped giving him pitching advice when he was 11 years old...