Here’s a pretty good read about Security Theater. As the link mentions, this might be more about Security Costs And Effort than actual security.
The Nationals ban backpacks – HardballTalk
So I don’t know about you, but I travel with a backpack for work. It has my laptop and usually some folders with documents I need. So if that can’t come to the game (weeknights) then I am not coming to the game (not that I was going anyway, baseball is terrible.)
Also, see what has happened at some stadiums In Europe. What about the backpack that is just outside the stadium?