Your guess is as good as anybody's including theirs.
I don't see any evidence of a joined-up strategy. It's all 'try this', 'try that'.
Starting yesterday evening GMT, I'm finding that if I do a search in one sort mode, and I switch sort mode before all the thums have downloaded, it returns no files after it moves off the first sort type.
E.g. I just searched cat and was in Newest as that was what I'd searched on last.
As it was downloading the 'newest' files, I switched to best match, and got no results, just a list of categories and 'tell us more', despite the fact 'cat' is still in the search box.
Doesn't seem to have appeared in the Bugs Thread yet.