Maybe a bit late to reply to this thread but:
Definitely possible! This is my third time applying, and just to give you an idea, the first time around I applied during my last year of undergrad and ranked in the bottom third of applicants (550/819 or something like that, don't remember exactly). The second time I applied (which was last year), I ended up getting an interview and placed high on the waitlist (which suuuucked emotionally, but it just shows you can improve like crazy just by doing a masters' and boosting your Casper score a little !). My pre-reqs were really really low,