I look at https://www.whattomine.com every week or so to see what to point to for (ASIC, GPU).

One week, much is (very slightly) profitable.
Another, like now, everything is not profitable at all.

Sure, BTC was $290 now $279 - but that's not enough to make the difference.

How do all the margins move so dramatically - but together? What am I missing?

Thanks!