It's a puzzle. Some of my hubs have low traffic but are mostly evergreenish so that must keep them featured? I just keep plodding on - I want to build up a body of work that lasts - despite the plagiarists and content thieves!!!
All I can say is that HP is trying hard to raise quality standards through a series of updates and readjustments and what not, so that more hubbers write more evergreen hubs and so little by little raise the bar. Hubs that were featured a few months ago may not now 'pass' the more stringent tests.
All of this is a wee bit frustrating for those writers who simply want their content out there, and aren't so keen on creating an evergreen each time they write - be it 450 words with one picture, 700 words with a video, one short poem with no image capsules, and so on.
Just as a print magazine or journal has an editor with a certain viewpoint and criteria for articles published so HP has their team working away in an effort to be successful. Different editors, new editors, change what appears in print - some articles previously accepted are rejected!! Similar things happening with HP I think.
Like it, lump it, loathe it, love it, leave it......