The name appearing on the front page of HN may have changed how many people were searching for the site and clicking its link, taking it from the spam bucket to the content bucket.
It may have also changed google's view on which people are searching for and visiting the site. Before, its search traffic was people searching for phone numbers, a random cross section of people who get spam phone calls. After, its a specific name brand being searched for by possibly well connected tech workers who are logged into google+.