Almost all the websites I track have very similar backlinking strategies. When 90% of the tracked websites see positive growth, you have to look at what they all have in common. That is the most glaring commonality. I understand that correlation doesn't imply causation, but sometimes you have to make assumptions based off the patterns you see in the data.
Also, the December update saw very little movement with the sites I track. The sites that did get hit (negatively), usually had some glaring issue with their on-page...e.g - page load speeds, which Google is putting a HUGE emphasis on recently.
Would you shed some light about your backlinking strategy then? It feels like you're doing smth right