There are fans in the outfield and around third base who ride certain visiting players, all visiting players, and sometimes even a member of their team who they are down on.
Players either learn to ignore them or get the name of “Rabbit Ears.”
However, players don’t ignore people who throw things.
As a matter of fact there was one foghorn Cubs fan in the grandstands at one game my wife and I attended who continually heckled Brooklyn outfielderDixie Walker. I guess he was trying to shake Walker up but it was a fiasco. As I remember it Walker hit a single, double, triple and home run and as he rounded third base on the home run he tipped his cap to the heckler.