Defensive Assist strength

for what is this? What the use of this?

When at 0, the players are in your complete control. You have to make sure they're facing right, that they're defending tight when they're supposed to, etc.
When at 100, the AI helps you in the defensive controls by making sure that your control player is at all times facing his opponent and playing tight. The players might feel stuck to their opponents though, and heavy to move, not responsive enough.

I find it best for me to have it at 5-10, so that I have most control over them, but the AI does the most basic things like making sure my player is not looking at the crowd when the opponent is right there in front of him.

When at 0, the players are in your complete control. You have to make sure they're facing right, that they're defending tight when they're supposed to, etc.
When at 100, the AI helps you in the defensive controls by making sure that your control player is at all times facing his opponent and playing tight. The players might feel stuck to their opponents though, and heavy to move, not responsive enough.

I find it best for me to have it at 5-10, so that I have most control over them, but the AI does the most basic things like making sure my player is not looking at the crowd when the opponent is right there in front of him.

thanks for the response sir.