Pitching Mechanics Question

Hello All -

I have a question for all of you about my son’s mechanics.

Now that we’re in the “off season” I have been doing some analysis of my son’s pitching and I noticed something that gives me pause.

My son’s a righty and when I video him from the 3rd base side I notice that after he releases the ball his arm tends to pronate/rotate outward so that his thumb is toward the ground and his palm is showing to the camera; it looks like he’s throwing a screwball almost. This has me concerned because it looks to be putting strain on the shoulder. However, his arm does correct as he follows through to the left side of his stride/left leg.

Looking at some video clips posted online I’m seeing the following players (J. Verlander, C. Schilling, T. Lincecum and J. Motte) do the same thing just after their release.

Is this natural? Like I said, I’m concerned of long term wear and tear on the shoulder.

Thanks in advance for the responses.

Its perfectly normal for the arm to do that. In fact, its less wear and tear on the arm if that happens.