There have been so many instances when a fan runs on the field and is tackled by security. Actually, often, the audience likes the action and change of pace. If they like him they cheer for him, if they don’t they cheer for the cops.
At an Houston Astros game on the 13th, one fan ran on the field in the bottom of the ninth inning. He charges center field, and when security comes, he bolts. He runs back to the seats and climbs up the side and escapes! The crowd loves it!