I don't think W/L is necessarily good either. Especially for CoD. If you put some of the guys on this forum on the same team all the time and end up playing randoms it's almost a guarantied win. The random guys might be pretty good but was playing against a stacked deck.
The above formula looks a bit like the BF skill calculation with has SPM, Objective and K/D included in the calculation. The problem with that is that it is relatively undocumented and most people don't know that it means