No problem, Chayo
The site is extremely unclear on the division between the Post-Bacc and MBS program, but from what I know of the MBS program, most students in that were Post-Bacc students that did not make the requirements one way or another (Missed the 3.0 or did not make the MCAT score).
As you see on the site, year 1 of the masters program looks very similar to the Post Bacc Program (minus some research geared classes), because they are virtually the same program for that first year.
I guess the best way to explain it is in a scenario:
If you make the grades as a Post Bacc - you are in. simple!
If you do not make the grades (just shy of a 3.0, or failed a class), you can either leave the school with a certificate, or request to enter the masters program. In this scenario, you do not have the same deal as the Post Bacc students, and you can turn that one year into a 2 year masters!
BUT I was in that danger zone of possibly not making the 3.0, so I talked it over with my advisor. She said if you do not succeed in the post bacc, it is a GREAT idea to join the Masters. Although the masters is not a guaranteed acceptance, if you do not piss any teachers off, maybe get a letter from one of them, and show you have a drive to succeed, it is easy to get in from the masters!
So, with my long winded message over (haha), Masters is not a guarantee, but you still have a HIGH chance of getting in. Ill even go far as to saying 90-95% of masters students get into the medical school without any problems!
Hope this helps!