After reading your post again. I like it. Pretty well thought out. Like Drew, I have been all of these numbers at times. But lets try to get more specific.
I find myself really enjoying Ghosts at a 3. Yet I have found myself at a 7 when my patience are running thin.
I had been accustom to being a 7-9 for BO1-MW3-BO2. Although I found myself being statistically better around 5-6 in BO2.
During CoD4-WaW-MW2 I was a 3. And just like Ghosts, a 7 at times depending on the map and gun I was using. Possibly why Ghosts has been very enjoyable for me.