During the warm up for a game, a heckler starts berating the pitcher. After the warm up, the pitcher takes aim and throws a ball at the heckler. (Assume that this is MLB so that throw is powerful). The heckler sees the ball coming and ducks. A fan who is leaving the stadium doesn't see it coming and is hit. Assume that all of this occurred in a spot in the stadium which is not "protected" from wild pitches. Who can sue whom and on what basis?

What is the possible tort and what defense to the tort?