Yes. The baby boomers swamped the colleges the year that Bush entered college.
I heard it was tougher to get into a number of colleges (even mine, which shall remain anonymous) because there were so many more applicants that year than in previous years.
I'd have to say that while I could accept that Bush was favored with acceptance to Yale because of his family/father, that wouldn't have helped him get good grades. Professors don't usually know who your parents are, and even if they do, they could care less.