Fielders set up in base path

[akalsey]

Also depends on the age of the players. If you're talking about a teaching league, just let the coach of the other team know. "Coach, your second baseman is in the basepath."

The coach will tell him to move up or forward a step and explain why he can't stand there.

Players at younger ages don't often pay much attention to where they're standing. At 8yo and under, they usually just stand on the worn out spot nearest their position.