MLB uniforms question

The Game Room
1

The rules for uniforms contains the following paragraph:

“If the undershirt is exposed then all the players on the team must wear matching ones. Numbers or other devices may be worn on the sleeve of the undershirt (for example, if it is worn with a sleeveless jersey), except that pitchers may not have such devices on their undershirt sleeves”."

hat is the reason for this rule?

2

I would guess that such “devices” (graphics) on the pitcher’s pitching arm could be distracting to the batter as the pitcher delivers.

3

I can’t think of any other reason…

4

This article speculates that distraction is the reason why.