Quite. Perhaps my memory is playing tricks but isn't it Rudy's story that he got the cuts fending of the guy he caught assaulting Meredith? If that were the case, it would make the evidence of the hyper-observant friends irrelevant. If that wasn't Rudy's story then how did he say he came by them? Contrast the enormous interest taken in the possibility that Amanda had an injury from which she might have bled into the sink etc.
I am totally confused by the Italian approach to combining circumstantial evidence. It seems to be permitted to forget parts of it when not convenient then remember them later when necessary. This is a far cry from the high-minded task Nencini set himself of constructing an organic, inclusive totality from all the logical elements, or whatever bollocks he was speaking when expressing his objective.
For instance, we know there were multiple attackers because, among other reasons, she was a karate orange belt and her father said she would definitely have resisted and the absence of signs of such a life and death struggle, specifically defensive wounds*, supports the idea that she was restrained while being assaulted. In that case, we would not expect to find the attackers nursing wounds of their own, right? But when we come to 'mixed blood' or 'mixed DNA' in the bathroom (from the large areas swabbed by Stefanoni as though she were the cleaning lady) it seems pro-guilt types are determined to believe Amanda picked up an injury which bled, a nose bleed or a bitten tongue, which proves there was a violent struggle in which the victim was able to lash out.