I am not completely familiar with the product profile of TEVA/Mylan, I will analyse their financials soon and get back.
Divis has a large CRM business which is very high ROCE and very high margin, which is why it commands a premium and not due to its generic APIs. For pure play APIs, a better comparison will be someone like Granules. Also, the long term (2004-2020) EV/sales average is ~7. The last time this ratio was >10 was in January 2008 when the value went up to 14x and then came down to 4.5x in March 2009.
I agree and thanks for pointing it out, its very useful 
I have tried to explain my analysis of different pharma companies here. I will get down to the valuation part soon