Would someone please explain to me in plain english what an (illegal) sidearm pitch is? I don't quite get the verbiage I've seen in various rule books (something about the "underhanded arm movement is more than 12 inches away from the parallel of the body..."). I'm sure the rule description is obvious to lots of folks, but I'm just not seeing it. Thanks in advance.

ASA 6-3-E The delivery must be an underhand motion with the hand below the hip and the wrist not farther from the body than the elbow.

I will quote from the NFHS book since it is handiest.

Rule 6 Section 1 ART 3...
A legal delivery shall be a pitched ball that is delivered to the batter with
an underhand motion.
a. Release of the ball and follow-through of the hand and wrist must be forward
past the vertical line of the body.
b. Hand shall be below the hip and wrist not farther from the body than the elbow.

I cannot picture any of these happening with a side arm pitch.

Here's the confusion I witnessed. From the top of the arc to about when the hand came around to the hip, the pitchers hand was noticably outside the plane of the elbow...but when the ball was RELEASED the hand and wrist looked in line with, or even inside, the elbow. Does (b) say that AS SOON AS the hand goes below the hip the wrist must be inside the elbow? Or just on release? Thanks again.

Think of it this way: Is the pitcher delivering the ball from the top of the windmill? If the delivery must be from below the hip, does it really make a difference where the ball is prior to the ball getting below the hip?

Can you actually differentiate the 100th of a second it takes from the ball dropping below the hip from the time of the release?

Sidearm ad naseum
 

Thank you all for the explanations. I (mentally) sided with coach that thought pitch was o.k. Unfortunately, all this 10 minute yelling match accomplished was to upset a young pitcher.

The rule is there to outlaw a sidearm delivery, not to have the umpire visualize a plumb bob line. I'd say it sounds like you are overthinking this and looking for technical violations.