I said pretty slim.
Not impossible.
Notice the difference?
I think three in one year (and again) those were three I know of, is more than any officers granted early outs to play professional sports. I would posit that it's more then "pretty slim", in fact, it would seem that it's at least equal to if not more then officers.
In fact the examples given include Napleon McCallum:
After graduating in December 1985, McCallum stayed at the academy as a recruiter. In 1986 the Navy assigned him to USS Peleliu (LHA-5), home ported in Long Beach, California, near Los Angeles, as a supply officer. McCallum played for the Los Angeles Raiders while on active duty that year; the military does not prohibit outside employment that does not interfere with service.[5] He rushed for his season-high NFL totals with 536 yards while splitting playing time with incumbent Marcus Allen.
The Navy reassigned McCallum in 1987 to USS California (CGN-36), home ported in Alameda, California and at that time sailing in the Indian Ocean, preventing him from returning to the NFL.[5] After serving his duty with the Navy until 1990, McCallum rejoined the Raiders. His playing time was limited as he played special teams and as a short-yardage specialty back, as Marcus Allen was the more dominant running back at the time. In the 1993 playoffs, he rushed for 3 touchdowns in a wild-card victory over the Denver Broncos.
So it looks like he honored his contract.
David Robinson:
Robinson was 6 ft. 8 in. when he was admitted to the Naval Academy, two inches above the height limit, but received a waiver from the Superintendent of the Academy. Robinson considered leaving the academy after his second year, before incurring an obligation to serve in active duty. He decided to stay after discussing with the Superintendent the likelihood that his height would prevent serving at sea as an unrestricted line officer, hurting his naval career, and might make it impossible for him to be commissioned at all. As a compromise, Secretary of the Navy John Lehman allowed Robinson to train for and receive his commission as a staff officer in the Civil Engineer Corps community. As a result, Robinson was commissioned in the Naval Reserves and only had to serve an initial active-duty obligation for two years. After graduating from the Naval Academy, Robinson became a civil engineering officer at the Naval Submarine Base Kings Bay in Georgia
So looks like he fulfilled the requirements as laid out by the Navy, as probably would not have otherwise been commissioned due to his height.
ANd of course Roger Staubach:
During his junior year at the Naval Academy, Staubach's color-blindness was detected. He was permitted to become the Naval Academy's first graduate to be commissioned directly into the Supply Corps, which did not necessitate being able to tell the difference between red (port) and green (starboard) lights or to discern the color differences in electrical circuitry.[5]
After graduating from the Naval Academy, Staubach could have requested an assignment in the States, but he chose to volunteer for a one-year tour of duty in Vietnam. He served as a Supply Corps officer for the Navy at the Chu Lai base/port (a secondary air base providing relief for Da Nang Air Base approximately 50 miles to the northwest) until 1967. Staubach commanded 41 enlisted men.[6]
He spent the rest of his Naval career in the United States, playing football on various Naval service teams to prepare for his future career in the National Football League.
I went through the list of others drafted out of the academies and it seems that they all did 2-5 years of active duty with 3-6 of reserve time thrown in after buying out the remaining obligation. I don't recall Ray Mercer or the other enlisted having to "buy-out" anything.l
http://www.usatoday.com/story/sports/ncaaf/2012/12/07/army-navy-game-nfl-five-year-commitment-relief/1747399/
