Based on the current prevalence of the date rape drug, I’d say it’s not just possible something was slipped in her drunk, it’s quite likely.
No one leaves a drink around in a bar these days. The kids hold onto it, keep it close, and watch it constantly. At a house party people are more relaxed but it’s still not safe. Given that the boys apparently did this once before and the girl was totally out of it then, I’d say she was probably given a drug.
There’s a huge amount of information that’s known but not reported by the MSM.
http://www.xojane.com/issues/steubenville-rape-verdict-alexandria-goddard
“I Am The Blogger Who Allegedly ‘Complicated’ The Steubenville Gang Rape Case — And I Wouldn’t Change a Thing”
http://www.localleaks.me/localleaks/steubenvillefiles/index.html
“The Steubenville Files”