LostTango,
You are correct about the calculation of determining points. However, I don't think this is right:
For Guard and Reserves, the actual percentage awarded is applied to the members
retired base pay. The retired base pay is calculated in a number of different ways based on the members circumstances. The different options are spelled out in this publication:
Physical Evaluation Board Forum - PEB Library - DoDFMR Chapter 7b (Computation of Retired Pay) .
The exception to the above is if the member has 20 years or more of active federal service and the years are multiplied by 2.5% and this number is larger than the disability award, then the member will get the higher figure as a percentage to be applied to the retired base pay (using the calculation from the DODFMR).
The years of service for a member is used in a number of different ways. It is used to calculate eligibility for the eight year rule, whether or not the member is eligible for CRDP, and (as described above) for calculating percentages that may be applied to retired base pay.
I think the main difference from what you described above is that it seems to calculate on how any member with 15.28 years would be compensated while the actual calculation will depend mostly on how the members actual situation (including what they actually earned on active duty, or time spent on active duty, among other possibilities).
Your post was helpful, though, in understanding how to calculate length of service.