Convex doesn't generate precise collision

I would suggest breaking the hoop off in its own model. The shape is very odd to get the shape you want.

You could just make the collision shape inside of Maya and bring it in with the model.

Hope that helps =)

Here is the example. This is the mesh my friends sent me (he works with Maya) and here is the result of using auto convex collision with maximum options.
Mind that the ‘‘Use Complex collision as Simple’’ option doesn’t work. It disables the collision completely.

I don’t understand how a circle is a wierd shape. Care to elaborate?
And how to do it inside Maya?

I assumed you were trying to import the entire goal as one model. If so, to the compiler its all 1 hull to breakup and calculate.