Alamy QC and CTR

So far Alamy has been ok to upload to. Until the other day i hadn't had a rejection although i also haven't had any sales.

The other day i uploaded a few illustrations of stage curtains along with an image of a cigarette at the end of a medical syringe which i like to think is my best quality creation to date. The curtains were not sharp but slightly diffused (as they were meant to be.)
The whole batch however was rejected due to just the curtains not being to their liking. I can live with that although i just don't understand Alamy's quality control procedure for rejecting ALL images in a batch even if only one fails. It seems a strange business model to me and a waste of time for reviewer as well as contributor. The syringe was later approved once it was uploaded (again) on it's own which seems to only confirm to me that Alamy like to cut their noses off to spite their face?!

Can you imagine Dreamstime rejecting 20 of your images because one failed/not required? Different site, different kind of market/buyers maybe but it still doesn't make much sense to me.
Anyone with a more insightful view of how Alamy's way of dealing with rejections (and binning anything else that was submitted at the same time) do please let me know as i would like to think i am merely missing something that means it's actually a good system. Not a bad one.

CTR:
I would also like someone to explain to me the rather odd (to me) statistics method they use. CTR (Click Through Rate) is still, after some reading, a mystery to me. Currently Alamy's "Average CTR" is 0.79. Whereas mine is 2.99. Is that good or bad? Who knows. I guess all you can do is submit saleable images and keyword properly at the end of the day ..