Rules of Baseball.com

In the Professional Edition, the only rule references are those for the Official Baseball Rules (marked below in green print). All professional baseball games - National Association of Professional Baseball Leagues (the “minor leagues”) and Major League Baseball - are played under the Official Baseball Rules only.

The Rule Differences Edition is simply the Professional edition with college and high school rule differences incorporated. In the RDE, you will find all references to the Official Baseball Rules, plus references to the differences to be found between the pro rules and the college (NCAA, NAIA) and high school (NFHS) rules. These references are indicated below in blue print. The RDE contains an appendix in which the rule differences are presented in their entirety (in the e-book, just click on the rule reference to jump directly to the appropriate place in the appendix).

“It is a balk if a pitcher does not have the ball but assists in a try to deceive a runner by

being on or astride the rubber, [8.05 Approved Ruling-a]
feigning a pitching position or pitch [8.05i], or
putting the rosin bag in his glove to make it appear he has the ball.

This is known as the ‘hidden ball trick.’ It is not necessarily a balk if a pitcher in this situation is on the dirt of the mound. [NFHS 6-2-5] [NCAA 9-3f]”

From
The Rules of Professional Baseball
By Jaksa and Roder

The NFHS and NCAA rule references indicate that it may be a balk if a pitcher is on the dirt of the mound during the hidden ball trick in a high school or NCAA game. Here are the NFHS and NCAA rule differences that you would find in the appendix:

You need the Professional Edition if:

You are a professional umpire.
You aspire only to umpire Little League baseball (uses pro rules).
You are preparing for professional umpire school and never plan to work amateur baseball.
You coach or manage in a professional league or Little League.
You are a fan of professional baseball who wants to better understand professional umpires.

You need the Rule Differences Edition if:

You presently work high school or college baseball, or aspire to those levels.
You work only professional or Little League baseball but interact with high school and/or college umpires.
You hope to keep up on the rule differences between the various levels.
You have not been able to make sense out of any other rules manuals.
You coach an amateur team.
You are a parent, relative, friend, or fan of an amateur player who wants to be fully informed about the game at hand.