I've always thought that a well-placed "accidental" case of a bat slipping out of the hitter's hand in the general direction of the mound would send an effective message.
I think that's an automatic ejection.
I dimly remember a case where Jose Roseboro whent after Marichal with a bat. Of course that was almost 50 years ago, so it might have been that Roseboro "returned" the throw to the pitcher and "accidentally" threw at full power an inch or two from Marichal's ear. (Helmets had no ear-flaps back then.)
