Actually there was webinar with Jeff Augen on OptionTribe. He mentioned short straddle strategy does not work any more, as market changed over tome.
In general he adviced to go short butterfly, because stock tend to be volatile at the expiry unnerving ppl with short straddles and often accept losses.
He mentioned short straddles used to work, but that's not the case now.
I have not researched that idea further though.