When you assign values to rankings, you're introducing Borda into the collection process.
Seems to me there is already a lot of Borda in the process when storing things as you are.
Not that there isn't in the pairwise matrix, but pw matrices do make it easier/more convenient to think about things as "who was ranked higher than who" versus "how far apart on the ballot was one candidate versus another". The latter way always seems to be subject to irrelevant alternatives mucking things up.
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