I read an article only yesterday which said the success rate of AA is probably "just" 8% or so. AA themselves claim the success rate is "75% for anyone who really tries", which, if you think about it, doesn't mean anything at all.
The article was specifically about this issue that AA blames it on the participants if their method fails. Which is pretty absurd, again, if you think about it.
It's like claiming I have a cure for cancer that works in 99% of all cases, but only in cases where it works.
(Edit: this is the article, it was on HN after all http://www.theatlantic.com/features/archive/2015/03/the-irra... )
Kelly J. F., Magill M., Stout R. L. How do people recover from alcohol dependence? a systematic review of the research on mechanisms of behavior change in Alcoholics Anonymous. Addict Res Theory 2009; 17: 236–59.
J.B. Kingree, Martie Thompson, Participation in alcoholics anonymous and post-treatment abstinence from alcohol and other drugs, Addictive Behaviors, Volume 36, Issue 8, August 2011, Pages 882-885, ISSN 0306-4603, http://dx.doi.org/10.1016/j.addbeh.2011.03.011.