Every MOC is different. In most cases, they use interview panels to evaluate candidates and they too differ greatly.
I certainly can't tell you how yours will work but I can tell you how the panels that I have been on would see it. The recommendation
letter would get noticed and could be a tie-breaker but the overall weight of grades and test scores might be a huge barrier for you.
I really don't know what "slightly above average student" means as it is very dependent on the school district/population that you're
comparing yourself to. From doing literally thousands of interviews over the past 27 yrs, a "slightly above average" academy hopeful
TO ME is a student with well over 1350 on the SAT and 3.8 unweighted GPA. In contrast, an above average student at the High School that
I attended would have above an 850 SAT (yes I'm serious) and about a 3.0 GPA. My latter case would not be competitive in most districts even
if they had multiple letters of recommendation from Medal of Honor recipients.