The screening prior to OCS has become more stringent and the info prior to them going has increased, we give them workout guides and such to reduce attrition, of course if someone shows up pregnant they are still going home.
And OCS has become a lot easier than AOCS was. The Marines had a mission at AOCS to attrite. You can screen all you want, but screening does not alleviate the head games and physical abuse that was AOCS. Candidates did not attrite for low intelligence, extra cirricular activitives on their resume or lack of desire. They attrited because life at AOCS was 12 weeks of pure misery and abuse followed by a week as a Candidate Officer where you recovered just enough to be barely presentable at your commissioning. There was no liberty until week 7 , no cell phones, no internet, no no personal time, etc. It was 24/7 under pressure with everyone who was not a candidate looking for a way to boot your ass out of the program or to get you to DOR. I am certain that in today's kinder, gentler PC military most of the daily stunts pulled by our DIs would be considered hazing or worst, and result in their receiving NJP at a minimum if not more serious punishment. The recruiters' job was to get you selected for the program, the AOCS staffs' was to weed out as many as possible. I watched AOCS class 13-83 get dissected. They started with about 80 candidates and their DI proclaimed that since their class number was 13, then 13 would get commissioned. He got the 14th left standing to DOR 2 days before they were to become Candidate Officers by 48 hours of constant harrassment and PT. He picked out who he thought was the weakest and ignored the rest for those 2 days. After he got his last DOR, he told the rest he had 13 and was done - congradulations!
AOCS was for pilots, NFOs and AIO (aviation intelligence officers). Everyone else went to OCS at Newport, RI and they started classes of 200 with 190 or so commissioning. OCS had maybe a 5% attrition rate. AOCS had a 65-75% attrition rate (my class started with 78 and commissioned 21. My brother's started with about 80 and commissioned about 20). It was a different time and a different culture.
After I got commissioned, I ran into a couple of the DIs in a Pensacola bar and bought them a few beers. They told me that most of the AOCS DIs had already completed tours as Marine OCS DIs and perferred AOCS because it had far fewer rules they had to follow than Marine OCS. AOCS let them use their imaginations in the most wicked and devious way possible. They continued to say that they respected every single officer that commissioned out of AOCS because they survived the hell the DIs put them through. They said that wasn't necessarily true of those commissioned from Marine OCS because the rules weakened the DI effectiveness. Again, this was the early 80s, not today. I have know idea what the DIs would think today but I suspect it is much harder to make it through Marine OCS now than Navy OCS.