PS4 dropped to $299 the week before the slim launch.
The price drop/slim helped boost the weekly average over August by 42%. That's bigger than the 2015 boost, +36%.
Because it sucked sales out of August, and the numbers were pathetic so a large % increase is not surprising. The actual sales increase was lesser. Lets take another look
2014 Aug+ Sept: 190k+538k= 728k
2015: 209k+ 354k = 563k
2016: 160k+ 285k = 445k
2017: 190k + ??? = ???
If we take weekly avg of August and compare to September, September 2016 was almost equal to August 2015.
2014: 47.5 to 107.6
2015: 52.25 to 70.8
2016: 40 to 57
2017: 47.5 to ???
Ignoring Destiny month, 2 years in a row the PS4 increased by 17k/ w. Leading to 64.5 * 5= 322.5k. But I am not that optimistic and personally predicted 310k, which would be quite the disappointing month. Anything less than that would be ridiculously bad imo, of course it could still happen with the Switch effect but so far it hasn't been true.