@Scott1665 the host, or whomever is responsible for inspecting the property between guest obviously did a poor job, as a basketball sized hole is significant. My guess would be that whoever did, didn't go into the backyard. However, in all honesty, I don't always inspect my backyard between stays, as there really is not much to "damage" out there. Aside from some patio furniture that is pretty sturdy (You would have to put some effort in to break it) there is only a grass yard in one case and a paved patio in another.
Ultimately, you have the right to deny the damages, and in this case of Airbnb hosting, it is always going to be a he said/she said type scenario because there really is no foul proof way to support that a particular guest caused damage vs it already being there or caused by another guest. It is very unlikely you will be charged, and the host will probably end up having to seek compensation through AirCover.
As for the review, there really is not much you can do to mitigate a potential negative one. If the host is convinced your party caused the damages there is a strong chance they will mention that in the event they review you. If this happens you can write a response to there review, that is brief and to the point but summarizes your side to the situation.
As other hosts have pointed out, moving forward, if you ever notice significant damage when you arrive it's always best to mention it to your host, just to cover your bases.