I haven't yet read the last few ones because I found the Aztec ones underwhelming. The Calculating Stars to A Desolation Called Peace was when I started feeling they were not so strong and decided I'd go read prior years instead. But I suppose the vagaries of 'winner' vs. shortlist probably take this. It is true that all those others you're talking about are much stronger. I do think that The Ninefox Gambit, The Fifth Season, The Three Body Problem are all just as strong as the ones you've mentioned.

Having read Network Effect and compared it to Piranesi, the two seem simply leagues apart. Perhaps the real thing here is that I'm over-indexing on taste instead of some object measure of quality. Piranesi was otherworldly in the way of Strange and Norrell but Network Effect was Yet Another Story in comparison.

And it's true what you say. Some of the past winners were also relatively weak. Downbelow Station seemed incomplete though I think Neuromancer was unbelievable.

It's just that when I went back and just picked old winners to read it felt like banger after banger after banger. The one where I only remember Kallikantzaros or Lord of Light or Dune or The Left Hand of Darkness. Ringworld I could see people being put off by, but it had this whole thing with the ringworld and the trifold symmetry thing and all that.

Then again, everything that comes now has to avoid everything that came prior, sort of O(n) problem. You can't be new when much has been written.