When you purchase tickets to a game, whether a baseball game or to some other professional event, look at the small print on the back. By purchasing a ticket, you are agreeing that the stadium or sports team cannot be sued due to things like flying pucks, balls, or players that may enter into the fan area.
These disclaimers generally hold up in court. By going to a game, you are assuming the risks associated with what could happen in the stands.
The only way a person could foreseeably be successful in a premises liability case for a foul ball injury is if the stadium or team was negligent or reckless in their duties to keep you safe. This could include defective netting or netting that was not properly maintained, leading to you getting struck and injured by a foul ball.