The snowball incident happened in 1968. Eagles started 0-11 then won two games that lost them the chance to draft OJ Simpson the following year so the fan base was pretty fed up with the season. The original Santa Claus couldn’t make the game due to a snowstorm so they pulled a 20 year old fan who happened to dress in Santa for the last game of every season to play the part. Then the sled he was supposed to come put on got stuck in the mud and his toy sack was a bag of dirty towels. So you had pissed off fans, a shoddy looking Santa and the rest is history. Guy who got pelted took it in stride,
Battery incident- the biggest one was JD Drew who was drafted by Philly then refused to sign. First game in Philly and idiots threw batteries at him.
A lot of the really bad behavior ended when the Vet got demolished. The 700 level at the Vet was notorious, Security even left the area alone.