Many Facebook publishers have been posting images along with a link to the relevant story as part of their status update, rather than sharing the link traditionally, which would include an excerpt from the story.  Images perform well on Facebook, and a shared image appears much larger in a news feed, over an image from a shared story, which is much smaller.

However, Facebook is making a change that will prioritize links shared via the story link format and will reduce exposure of posts that upload a photo related to a story then simply link to the content via the status update area.

This is how a post is displayed when linking to the story with excerpt.

And here is how the same story appears when someone uploads a photo and then shares the story link as part of the status update.
Facebook feels that people would rather see a short blurb from the story linked to, so that users are not blindly clicking a link that may or may not have the promised content.  This also helps people be aware of potential phishing or spam, as shared links not only display the excerpt but also the domain name and author information from the story.

We’ve found that people often prefer to click on links that are displayed in the link format (which appears when you paste a link while drafting a post), rather than links that are buried in photo captions. The link format shows some additional information associated with the link, such as the beginning of the article, which makes it easier for someone to decide if they want to click through. This format also makes it easier for someone to click through on mobile devices, which have a smaller screen.

This change will now prioritize those stories with links that are using the link format, over those that simply have the link in the status update field.