I am a bit baffled too! I know that my application consistently ranked high in the internal selection process. Although in my case, my undergraduate gpa was so low, that I was unable to even apply for a MA SSHRC. My application was written quickly and only with a few revisions (and I knew I had a typo... gosh), but still was considered as strong as the current PhD students in my department. I think next time around I might send the draft around to people with different disciplinary backgrounds, and more explicitly explain why it is an "important" work. That's probably the only improvement I could make in such a short time...
To share my qualifications
4.0 MA gpa, 3.33 undergrad gpa
4 RAships
4 TAships
5 non peer reviewed publications
1 peer reviewed publication
0 conference
fellowships/awards but nothing that is extremely prestigious
very very strong letters, probably almost as strong as they could be
strong application with a typo, but I think people from other departments might have a hard time understanding why it is an important project although they get what I am proposing