Are you attributing all drug usage in your territory as your "sales"? The truth is that 95%+ of what occurs in your territory, would happen whether you were there or not;besides that, the costs of a rep go far beyond their salary and include salary, pension costs, 401k costs, medical benfits, car associated costs, travel and entertainments costs, product promotion costs (lunches), etc.
Remember drug sales is not really selling anything! It is really difficult to attribute value to a specific rep. If you dont believe me, just look at any ranking report, and notice that and see that "vacant" territories are rarely at the bottom, and many times are in the middle to top of the rankings. Besides that, look at BioOnc, where there are 5 or more reps calling on the same office, do you really need that many reps? If you cut BioOnc by 20% or even 40% would sales decrease by that amount? I doubt it would decrease at all.
I have seen sales forces cut, with zero impact on sales. "Sales" people are a MUST in the drug industry, but reps really do not "sell",they "promote" and are merely extensions of marketing. They are very importsnt, but do not have a linear relationship to the generatio of $$$.
Besides, if you believe that a rep is directly responsible for all $$$ in their territory, why don't the $$$ go to zero when reps leave?