Like joe said there's too many reasons to name.
loss of balance,Tripped,chin check,etc........
The thing is to know what to do while down there.
Yes against multiple attackers the ground is a disadvantage ,but you can even the odds.If your quick and know what to do.Take out some knee caps or sweep everyone attacking you.Most people go down and just cover up and that ain't gonna work son.
At that instant it's all about survival do what you have to do to make it out on your own.Only 60% of fights go to the ground for one reason or another.Most end when someone hits the ground because their usually out cold.
jmd161
