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?
The list in WMT has many issues. It needs careful study over time. I don't find it anywhere near complete or representative.
The cache date is merely the date of the cached page you see. Be aware that ranking data, and the page title and the snippet in the SERPs are each stored in a different database, and may all be out of step with each other - and often are.
Yeah have to agree with your opinion on GWT links data. I find that it misses a lot of good links in our site link profile. It somehow has a tendency to 'pick up' only links in certain types of sites such as blogs, etc.
You are saying that even though if the cached date is behind the day on which the link is secured, Google still takes into account the link juice passed by the new link?