This article talks a lot about how low click rates don't matter -- but that wasn't the issue brought up by the WSJ. The key take away is that, even if you ignore clicks, impressions are twice as expensive as your reporting suggests.
> An astounding 54% of online display ads shown in "thousands" of campaigns measured by comScore Inc. between May of 2012 and February of this year weren't seen by anyone, according to a study completed last month.
> Don't confuse "weren't seen" with "ignored." These ads simply weren't seen, the result of technical glitches, user habits and fraud.
http://www.wsj.com/articles/SB100014241278873249040045785371...
> An astounding 54% of online display ads shown in "thousands" of campaigns measured by comScore Inc. between May of 2012 and February of this year weren't seen by anyone, according to a study completed last month.
> Don't confuse "weren't seen" with "ignored." These ads simply weren't seen, the result of technical glitches, user habits and fraud.