I feel it's ridiculous to think that eBay is manipulating the ratings.
I don't need to know which specific items are related to a particular rating, my shipping time star is 4.5 I know full well why it is, my description star is 4.9 and I know exactly why that is as well. It's not a ratings change caused by a single transaction that is important it's the trend. I would also think that in many cases (for me anyway) if I have a buyer who dramatically downgrades me (leaves a 1 or 2) I'm usually well aware of the problem.
In the OP's case I know exactly what is causing your dsr ratings. What I don't know (only the OP knows) is if it's possible for you to do anything about it of if the "return" of improving your rating is worth the "cost".
Take my shipping time star at 4.5, there are two reasons it's low, first is that I don't ship often enough, some orders sit for a week after payment before being sent. Second is that I sell a high proportion Internationally. I could ship more frequently and I may start to do this on the other hand I wouldn't give up any of my International business in exchange for a slight uptick in my rating.
As for transparency,is possible that the Sellers Dashboard which will be available soon will provide us with the info to better monitor and understand the ratings. That is it's proposed intent so I'm going to wait and see what they provide. When they remove the ability for sellers to leave retaliatory negs perhaps they will allow us better access to the background data.
One thing I do fear is that sellers that abused the current system will start to abuse the new system, if it gets bad enough with enough unjustified "false positive" comments being left we may lose the ability to leave any comments at all.

"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.

"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.