What AaronJB stated above is 110% true...it was true almost 30 years ago when I went through AOCS and it is true today (congratulations regarding commissioning, Aaron!). What Aaron is talking about (correct me if I am wrong) is that when an individual arrives at OCS in excellent physical condition, that individual will be able to better concentrate (and therefore perform) in their studies due to less fatigue. I saw it happen almost 30 years ago...individuals showed up for AOCS in marginal physical condition...so when it came time to pay attention in the classroom, study at night and perform on academic tests, they could NOT due to the fact that they were physically fatigued from PT...and of course they could NOT perform in upcoming PT because they were fatigued and sore from previous PT. Another item...when an individual arrives at OCS in excellent physical condition...that individual is already displaying a motivation and desire to succeed...and it will be noticed by the instructors.
I agree. You don't have to be in stellar shape to "make it through" OCS. This isn't BUDS. However, the better shape you're in will eliminate the stress of PT and beatings. Also, we're dealing with senior Marine Corps Drill Instructors. They can spot weakness from a mile away. When your class is getting destroyed in a beat down they notice who continues to put out. The beatings are designed to fatigue you in just a couple of minutes. The guys who are in shape (and motivated) will be noticed by the DI's. You won't get a cookie or even a verbal acknowledgement, but you'll probably get their respect. I trained super hard for OCS and I never received a single individual beatdown from our DI because I sounded off and performed well in beatings. I sucked at drill and making racks too so that just further proves my point.