If your university is not highly ranked, and you are not in the top 3 within the UNIVERSITY then your chances are *very* small, given the especially limited number of awards being given out. It's arguably unfair, but definitely that's what the past track record or applications/awardees indicates...it's just politics...
Advice...be ranked first in the university, if it's small, top-10 if it's large (UofT, Alberta, UBC, McGill, Waterloo). Easiest way to improve ranking is to be involved in cutting-edge research that can get headlines - look to health, energy, bioinformatics, neuroscience, nano, quantum information, high performance computing and intelligent data analysis, etc for your application area will make things significantly better. These make headlines...