I was at USMAPS R Day last Friday and the Commandant discussed this issue and Just a Mom is correct, it's usually math and the focus of USMAPS is success at USMA, academics first, athletics second, it's their (USMAPS) mission. The power point slide show last Friday, had a graphic showing the averages of the USMAPS Class of 2010 SAT scores and there are actually some students there with 700+ SAT math scores! The chart also showed the the average math and English score was just under 1,150 with direct appointments average around 1,270, this is from memory but I know the difference was around 150 points less at USMAPS
Now they might have another agenda not publicly discussed but, he went over this subject pretty throughly.
My son is at USMAPS now and is not a recruited athlete, he also only took pre-calc in high school and had a competitive math SAT score with a lot of leadership (JROTC / Scouts) behind him.
Momof2cadets has a point also, another possible reason is the Nominating source (in my son's case) told him that he was their number one USMA Nomination but, he wanted him at USMAPS first and asked how he felt with an extra "plebe" year. I guess my son gave him the right answer because the MOC military liaison called us a week later and said he was going to USMAPS. About a month later the appointment came in February.