My website was ranking first for a search phrase. It was getting good traffic from this phrase. Around the 11th October my site slipped to second with a modest effect on traffic. A couple of days after that it was back up to first and is still there. However, my traffic from that search term is about 20% of what it was. I can't explain it. My total traffic from google is less than half so more than just this search term have been affected, and can't be attributed to google not sharing search terms for signed in users. But if I am still number one theoretically I should be getting the same amount of traffic from this term correct?