Hey Fraser,
So I found something interesting while playing with my duma. As I started getting better I noticed I was being matched up with players more around my Score Per Minute. What really made me believe was my first game I was playing with someone and we both absolutely went crazy on the other team (I went 46-9 he went 53-7). Next game around he "randomly" appeared on the other team and as a result the game went for longer and my team won 100-95. This was of course on Black Ops III. Seeing this I decided to turn off my profile and switch it to non gaming and run some torrents while live streaming. I then realized my score per minute not only went up but I was winning gun fights I clearly shouldn't have won. From there I believe especially on BO3 that lag compensation trumps SBMM.