Soros hasn’t yet bought the Rasmussen polling firm during the time frame you reference. He may have bought it in late 2013, but iirc, the sale wasn’t made until early ‘14.
Incidentally, I noticed the change even before I found out Rasmussen had sold to Soros. I had been in the habit of visiting Rasmussen’s site daily. All of a sudden, Every Single Obama Poll he did was an outlier. Worse, Every Single Obama Poll was an average of 4 points higher on approval than any other poll. W’out knowing what had changed, I concluded Ras had gone over to the dark side, & ceased visiting his site.
It was about a mo later that I learned Soros had bought Rasmussen’s polling co. Since then, the pro-Obama slant has continued unabated. Here, you can see it for yourself; go to the following site, & compare Ras to the other pollsters for several wks. You will see Ras consistently ~4 or 5 points higher on Obama approval:
Incidentally, the above site is best for polling info overall. RCP has been bought by a Chinese co. But be that as it may, it averages in Ras’s artificially [and daily] Obama-approval polls, so the RCP average for POTUS approval is worthless. Check the pollhealines site for regular, unfiltered updates.