If you want to spend lots of time it's IS possible to figure out who left what.
I wouldn't bother...
You might not be right about who left what,
You can't contact them about it anyway,
Blocking buyers who don't like you is kind of pointless because they are unlikely to buy from you again,
And finally if you received a low rating you either can easily tell who it came from because of known issues with the transaction or you find out you got a low rating that was "unwarranted" and thus nothing you can do to avoid it in the future.
Unless you have pretty conclusive proof that the ratings given were malicious, the purchase made with the sole purpose of leaving poor ratings, there is nothing that eBay can or will do
( you aren't even supposed to be trying, it's a violation to try, I think)
The violation is not in the "finding" it's the harassing of the buyer that is a violation.

"What else could I do? I had no trade so I became a peddler" - Lazarus Greenberg 1915
- answering Trolls is voluntary, my policy is not to participate.