I think being 2weeks since July 24th we can conclude that the spike was not random network variance. The 10% spike was most likely new ASICs going online. The 10% gradual increase in the past 10 days was perhaps other algo users switching to ETH as their algos fell to ASIC (which is ironic since ETH is no longer a GPU haven).

Anybody mining ETH right now on GPU either has dirt cheap power or is mining Hopium because the cards like the 1070 and the 1080 are depreciating faster than the value of the ETH they can mine. Even Ryzen 2 CPUs are tanking in price with Ryzen 3 CPUs spanking everything.