This seems to be exactly what is happening, Yahoo has ranked my site at #2 and #3 for two specific blog posts. I'm very surprised to see the amount of traffic I am getting from Yahoo.
In my case, Yahoo still performing badly. Google get me around 1000 and yahoo only 10% of G. Wondering when I can get such a huge traffic from Yahoo. 6000 a day is insane for my level. Congrts anyway! Make sure to note down all of the high traffic keywords and it might be useful to double the traffic in the future.
The Yahoo traffic is not consistent though, Google search traffic is still my main source of traffic. I have several sites, most are commercial advertising related.
I had once getting this type of traffic from Yahoo, but it did not last long. Just around a month, and it quickly subdued.