[rev_null]

If you divide the total revenue by the number of HR employees, you will also get a much larger number. (Total revenue / total number of employees) will always be less than (total revenue / subset of employees).

This is not a very good metric.

[NeverFade]

In a company like Facebook, who is directly responsible for the revenue? And who is working support roles?

If you laid off 90% of HR, how will that affect revenue? What about laying off 90% of the engineers?

[chiph]

HR, Accounting, etc. aren't directly revenue-producing. You could make a good argument that Sales headcount should be included, though.

[yibg]

Divide by number of product managers then, even higher per headcount.