Avengers vs FF/ X-Men

Avengers:
Captain America
Thor
Vision
Iron-Man
Wasp
Black Panther
Scarlet Witch
Quicksilver
Hawkeye

Vs

Reed Richards w/prep
The Thing
Invisible Woman
Human Torch

and

Wolverine
Cyclops
Psylocke
Bishop
Iceman
Angel
Gambit
Rogue
Beast

This seems like a huge mismatch. Why are the numbers so one sided?

Because of Scarlet Witch and Thor

also Avengers get Namor and Ant-Man

How bout Defenders come in and beat everyone?