My Homepage Rank suddenly decrease by 75% in Google Why ?

[GIRI Patel]

Hi, Sir My site homepage rank was at 16th in Google Search on 3rd Oct'2013, suddenly it was decreased to 75%. May I know the possible reason ?

My site is - Sarkari Naukri

I have reccenlty installed cloudflare for decreasing server load, I have seen some other high rank site also using it like successcds.net, So I hoped there was no issue to use and I installed it. withing 5 days may rank goes down, 

Can you tell me the reson as I am using original content on my site and my SEO also good and I have 162 alexa backlink. So no other issue and this type of sudden change make me surprised. Pls help me. 

SCREENSHOT ATTACHED , TAKE A LOOK PLEASE.