In August, Google launched a new SERP feature called in-depth articles which feature long-form content about broad search terms. Currently, this block of results appears at the bottom of the SERP and consists of three results, each with an image, title, publisher, and description. In order to give content a chance to appear in this section, Google advises 
implementing schema.org markup, authorship and publisher markup, pagination and canonicalization, and First Click Free for restricted content.
In the brief time that in-depth articles have started appearing, it appears that Google’s algorithm heavily favors authority signals when serving in-depth results. Some publishers that frequently appear include The New York Times, The Wall Street Journal, and Huffington Post. One question that remains, however, is what purpose these results are serving. After a few quick searches, in-depth articles appear to miss the mark in providing results that match user intent. Take for example a basic search for the word “candy.” Below are the in-depth articles that Google serves:
A user interested in “candy” might be looking for a broad definition or a historical background. Instead, they get an interview with Ryan Gosling, a restaurant review for a place called Dirt Candy, and an article about a cheat to use in the game Candy Crush. Not a single result is actually about the confections known as candy! Because all the results are from highly authoritative publishers, each article is likely to be well-researched and well-written, but none of this matters because none of the results are relevant. This lack of relevant results isn’t exclusive to “candy.” Take as another example a search for “jazz.”
The first result might be relevant, but the second two are most likely not. One is a personal essay and the other is a highly specific article about one group’s historical hatred of jazz. It’s unlikely that users who entered the extremely broad query “jazz” were looking for any of these results – the Wikipedia article at the top of the SERP, which provides broad information, would likely satisfy their search intent before they reach the bottom of the page. However, Google appears to be specifically targeting broad terms when serving in-depth article results. These queries aren’t reserved to single word queries, as demonstrated by Moz’s analysis 
on in-depth articles, but these broad queries require the search engine to make wild guesses about a user’s intent.
In-depth articles served for broad term search queries, such as “fish” generally have vastly different kinds of results featuring specific pieces published across a wide range of dates. In the example below, the search results provide users with fish-related articles ranging in focus from economics to neuroscience to ecology.
There doesn’t appear to be any underlying theme connecting the various topics represented in the in-depth results. Instead, Google seems to be carpet bombing users with a wide variety of long-form content, hoping to capture their intent based on an otherwise unclear search query.
What’s more compelling is that the in-depth results that appear for each given query appear to remain constant no matter how many times a user performs the same search. Searching for “fish” provides users with the same three results in the same order every time the search is performed. It will be interesting to see if Google starts to swap in-depth article results as they learn more about the user and are better able to serve results that satisfy individual search intent.
At this point, however, the algorithm for in-depth articles appears to put too much weight on the prestige of the publication at the expense of the article’s topical relevance. In a sense, Google is attempting to use authority signals as a proxy for both high quality and relevant content. They may have nailed the high quality aspect, but relevance may be harder to achieve. At present, it seems a little too ambitious. It would be interesting to see what sort of click-through rate these results are getting on the SERP to determine if users are actually responding to these results. Until then, it’s difficult to ascertain what sort of explicit SEO value the in-depth results have for brands and marketers who are not writing for major publishers.