It may well be oddly. I have had the same thing, where I've had to exclusively play objective, getting less kills as a result while my teammates steal my crests and fail to capture in control. Look at the matches I played yesterday on my titan (trying to level him as he's been idle since vanilla). I consistently have the highest efficiency on the team but, am forced to defend zones and kill enemies/save team mates who are just running in like cannon fodder. After 5 matches like this (5 win streak) I am now convinced the algorithm is doing a skill total tally for each team so my teams average is being based on me and maybe one other in the team. Looking at some of the 0.xx efficiencies on my teams it's getting rather stupid. I think the only time I got less than 1.0 was when I was dropped into a match near the end and it was clear that the person who had left was just ending up getting three manned while the rest of the team hid (exactly what happened to me!).