Update from a post on TR Forums:
My load cycle count for this drive is over a million (!). Apparently the Green series parks its heads after 8 seconds of idleness, and for a computer that's on 24/7, it adds up. The word on the street is that the load cycle design limit is 300k, which is mildly concerning. I skimmed a bunch of threads and I couldn't find a clear correlation between LCC and failure, but it's still worrisome. The takeaway is that there's a "wdidle" utility for setting the idle time.
I'm keeping my fingers crossed for now. As soon as I get a chance, though, I think I'll swap it out and relegate it to backup duty.
I was aware that this was an issue for Linux, because Linux tends to "touch" mounted filesystems at intervals slightly longer than the default park timeout on the WD Green drives.
This was with an AACS drive, not an EARS.