User blog comment:Rapacious/Rapacious's sexy guide to understanding ranged AD builds/@comment-131.174.224.196-20120201222441/@comment-4073002-20120203184230

Attack speed and crit stack additively, not multiplicatively, so it will only be ~2x damage when you have no other items. You're also only comparing it to the ArP parts of LW and BC -- they do give other stats.