What happens when the cache of an article from which you get a link from is dated a few days before you secured the link? Does that mean the Big G has not re-visited & re-indexed the article again, thus not taking the link juice into account when calculating current rankings?
And how accurate do you find the link diagnostic in Google Webmaster Tools? (ie. Links to your site). Does it really portray your most recent & up-to-date link profile?