The pigs are not smart, their brain are very small. Their structures are weak and not well made.
The birds are strong and well know about physics. They are extremely angry and worried about the eggs that they doesn't think about if it's going to injury them. They also sometimes doesn't use the slingshot and only their strength to defeat the pigs.
The pigs often doesn't strike back or are slow to do it so the birds win.
I agree 900%
What do you think?