When I applied to STA-21 I talked it over extensively with my CO and XO (both Acadamy grads). My biggest question was why were so many Admirals from the Acadamy and so few from elsewhere...and this was their response:
In the past (50's, 60's, 70's, maybe 80's) those attending a military academy were considered elite simply because they were getting to attend a college (read: any college) espcially for free. The competition to get in was tough, and graduates were expected to make a career out of the military (think Adm. Mullen types). The Navy used the Academy as a primary commissioning source because not many people could afford to go to college.
Today, college is much more accessible to a larger percentage of the population. That said, the Navy has extended its officer recruiting to STA-21, BDCP, OCS, ODS, etc...since more people can afford to go to college the Navy has a much larger recruitment pool. As we see our peers move through the ranks, less Academy grads will hold top spots as the officer pool becomes populated with other commissioning sources.
The bottom line was that for a long time, the Academy was the most significant source breeding career Naval Officers, now, that is not so much the case. Today, your commissioning source doesn't make a bit of difference.