Not to throw rain on the parade, but the numbers are a bit more complicated. Each year, about 300 slots are given to NAPS/Foundation students. Because these individuals are essentially guaranteed an appointment if they are fully qualified and want one, the remaining ~1700 fully qualified applicants with a nom are competing for ~900 spots. So, the odds are closer to 50/50.
To further complicate things, ~800 slots are set before USNA looks at the national pool. This comes from the ~540 MOCs (including reps from DC, Guam, PR, etc) X 1.25 (remember, each can have up to 5 mids at USNA at a time which means once every 4 years, they'll have 2). This equals ~675 -- although that number can fluctuate because some MOCs have no qualified nominees in some/all years and/or the "5th mid" for each isn't evenly spaced out. Add in another 100 Presidential nominees and an additional 25 for "others" (e.g., direct from the fleet, ROTC noms) and you're pretty close to 800 slots taken before USNA looks at the national pool. There are now ~900 candidates (1700 less the 800 who now have appointments) competing for another 100 slots (900 available less 800 appointees).
The above numbers above are APPROXIMATE and could EASILY vary a bit from year to year so this is not set in stone. It's intended to explain that the system is a bit more complicated that simply looking at 2000 candidates vs. 1200 slots. I would also note that USNA actually extends somewhat more offers than slots b/c some will decline their offers; the above is based on the 1200 who are admitted (vs. the 1500 appointments tendered) so the odds are actually a bit better when you add in the extra appointments that are extended to get the expected "yield."
The end result is that competition in the national pool is quite fierce and, in the end, there are MANY TERRIFIC candidates who simply lose out to too few slots.