econman - 12:10 pm on Mar 20, 2012 (gmt 0)

try to look at things logically

What does it mean if a high percentage of outgoing external links on a site are broken or no longer take you to the same content as when the link was originally published?

It tells you that the webmaster isn't making much effort to maintain the site.

Back when the SEs were only thinking about "relevance" this would not have mattered.

Now that they are thinking about "quality" it does matter.

Logically, this signal would be most meaningful in a more complex context, which also considers the age of the surrounding content, and the degree to which that content "needs freshness."

For older content which doesn't need freshness, a willingness to go to the effort of periodically verifying that outgoing links are still good is a sign that the webmaster cares about their users.