Here's a copy of the email @Ironholds sent out about this testing effort:

From: Oliver Keyes <okeyes@wikimedia.org>
Date: Thu, Jan 28, 2016 at 4:44 AM
Subject: [discovery] Portal A/B test results available
To: A public mailing list about Wikimedia Search and Discovery projects <discovery@lists.wikimedia.org>

Hey all,

A couple of weeks ago we ran an A/B test on the Wikipedia portal
(www.wikipedia.org) to test whether a more prominent search box,
optionally combined with additional metadata such as small images in
the search results, would increase the rate at which people clicked
through from the portal to one of our projects.

We are delighted to say that the test showed a 1-5% increase in the
clickthrough rate, where both a prominent search box and metadata is
used. Accordingly, once we've resolved concerns about the design's
non-JavaScript usability, we hope to deploy it for all users.

The report can be seen at
https://commons.wikimedia.org/wiki/File:First_Portal_Test.pdf - please
let me know if you have any questions.

For Discovery Analytics,

Oliver Keyes
Count Logula
Wikimedia Foundation