Eh I'm not convinced that people who buy a Destiny bundled PS4 4 days ago are going to run in mass to Amazon to pre-order COD:AW when it's almost guaranteed most of them won't have even finished the story of Destiny by now
Whereas with the Gamescom introduction of COD AW's multiplayer being heavily Xbox branded and in early April, I can totally see August pre-orders being skewed by that
Furthermore though I don't really hold august or September amazon rankings to be super interesting at the moment again because COD AW hasn't broken into the Top 100 for the year which it will almost assuredly do thus pre-orders haven't got to critical mass yet
We'll see, but these are the same indicators that we saw with Destiny and Watch Dogs and I think most know how that went. In August the Xbox One numbers were far ahead of the PS4's in sales. In September the sales are basically the same even with probably much more new PS4 owners this month than XB1 owners.
I'm not saying they all immediately pre-ordered CoD, but it's the next real BIG game out for the PS4 so I could see many doing so as it would be their next purchase.
It hasn't reached mass pre orders yet, but many people have already pre ordered and I don't think that with all the Activision marketing in the coming weeks promoting the XB1 version, bundle, exclusive content, xbox brand strength, etc. that the PS4 version will make up the current gap. Sure, it may be ahead by 1 spot RIGHT NOW due to the massive influx of new owners, but this hasn't been the case since the game was shown off at E3 and there is no real gap in September currently.
Even the XB1 version of Destiny was ahead of the PS4 version for small periods, so I don't think this is really indicative of the larger trend we've seen.