Baseball's starting and...

A smaller-than-normal bat used by the coaches to hit fly balls to outfielders as practice.

isn't it also a colloquialism for athlete's foot

I would say it's a thinner than normal bat.
As I recall, it has normal length.

In Spanish there's a baseball verb called "fonguear".
When every batter easily hits the ball into the outfield, the pitcher is being "fungued".