I have one problem with the calculations.  Overall it's a good article, and more metrics are always useful, if they're accurate.

He lists the calculation for data flow as: Data Flow = Size of Data Element * Number of times it is accessed  -- and uses AverageRecordSize to represent Size of Data Element

But there's a big piece missing, namely the number of rows.  A table scan or index scan will retrieve each row of each table/index.  So we should be multiplying by total table size, i.e. AverageRecordSize * NumberOfRows, or better yet, NumberOfPages.

So, a wide table with a few rows will come across differently than a narrow table with millions of rows, even if they take up the same number of pages.  I think it's best to think of table or index data flow in terms of pages, since that's the memory allocation chunk size and basis of disk retrieval.