Skepticism is a good thing, and I am also trying to think things through by looking at the marks and bruising on her face.
1) A big bruise at the (left?) eye,
2) what looks like small bruising below the left cheekbone,
3) smaller bruising under the right eye,
4) another smaller bruise at the outer portion of the upper right cheek,
5) a little redness/roadrash on the left cheek, too.
She says the guy hit her in the back of the head. I wonder if that caused her to hit the ground face-first and all that facial bruising came from that?
Would that kind of face-first "landing" mash her nose into the ground and cause the bruising along the facial areas that appear in the photo? No burst blood vessels in the eye, so it doesn't look like she got socked straight in the eye.
I believe her. The police were involved as was the McCain campaign.