Probably because of its preference for the mission for which it does get allocated (as generated by the allocation linear program). Here’s a simple example:
Preference | You | Me |
---|---|---|
1 | Vanilla | Vanilla |
2 | Chocolate | Strawberry |
3 | Strawberry |
We have 1 pint of vanilla ice cream, and 1 pint of strawberry. We both favor vanilla first, but since my preference (#2) for strawberry is higher than yours (#3), I'll get stuck with my second choice & you'll get your first choice.
To minimize the “cost” (the sum of the preferences), you get vanilla, I get strawberry.