Last year 1,73,735 candidates took the CAT admission test through which the IIMs admit 3,335 MBA students. That's a 1:52 ratio.
Now you could argue that not everyone who takes the CAT is an IIM applicant. So let's take IIM Ahmedabad's (slightly dated) data for 2006-08 admission [1]. Of the 1,44,027 who applied to the institute, 273 secured an admission. That's a 1:527 ratio.
Harvard Business School's admissions:applications ratio is 1:12 [2]
I'm sure you have an explanation of why a 1:527 ratio is "not that hard".
[0] http://www.business-standard.com/article/management/boys-rul... [1] http://www.iimahd.ernet.in/institute/about/key-facts/institu... [2] http://www.hbs.edu/about/facts-and-figures/Pages/mba-statist...