In my opinion, it is the transitional phase and not indicative of any trend and one should look at CSE 2011 result as an aberration. Candidates with Hindi medium have performed reasonably well in past and achieved higher ranks in Civil Services Examination.
Keeping an optimistic view, I see no reason why Hindi Medium result should go down in future.
The cause which becomes evident is that in the Prelims 2010 itself the evolving examination blueprint surprised many Hindi medium candidates and a large number of the candidates adopting traditional approach in preparation had found it difficult to cross the first hurdle.
And then, came the new-look Preliminary Examination 2011. Probably, the anticipated shift in the preparation strategy was missing among majority of Hindi medium candidates and added discomfort came from the fact that many good candidates and majority of those who had only one attempt left, preferred to sit on sidelines just to observe the new pattern and trend of questions asked.
I will refrain to make any comment on new-look Prelims and is it favouring English medium candidates or not; what I sense, most of the Hindi medium candidates who ignored CSE 2011, today, after looking at final result and written marks cut-off, must be repentant.
It is not that Hindi medium is completely washed off this year. There are good numbers of successful candidates and you will find many successes with Hindi medium. The only thing is that the presence of many Hindi medium toppers within top 100 candidates motivates and encourages future aspirants, which is somewhat missing this year.
I sincerely hope and wish that the result of Preliminary Examination 2012 will bring back the smiles on many Hindi medium candidates which is missing at least for last two years.