Actually it really doesn't matter how many they have at the SA currently, because in the end most MOCs like to spread the wealth. So if they have 2 spots open, than traditionally they will submit 2 separate slates of 10 each, not 1 slate of 10 for 2 spots.
That means your chances of getting charged does not necessarily increase just because they have 2 spots; it is still 1 out 10 that can get the charge. The nom gets you in the door, but that doesn't mean when you get apptd that MOC will be the one charged for your apptmt.
Also, if you read the reg., it states up to 5 at any time, it does not state will have 5 at all times.
Member is correct the date for all MOCs are the same regardless of the SA. They are also correct that what is more important if trying to see your chances, is to contact the MOC and ask for their SA personnel. They can tell you how many applied this yr. From there you can ask if they nominated 1 or 2 slates. Ask for the specific SA, the reason why is that demand for certain branched are higher in certain geographic areas. Applying for USMA from CSprings is probably not as competitive as applying for the AFA from that area.
Finally, remember that just because the MOC has 5 ty, doesn't mean they will have 5 charged come Aug...cadets leave be it graduation, academics, or personal reasons, thus, they could have only 3 next fall charged to them.
Flipside, maybe they have 5 right now, and none of them leave(2 C2C, 1 C3C, 2 C4C---no C1C), that would mean next yr they would have no ability to nominate since they have met their legal limit.