They were just quoting the article: "While they did say that this was the biggest overhaul to their engine since the 2009 “Caffeine” overhaul (which focused on

They were just quoting the article: "While they did say that this was the biggest overhaul to their engine since the 2009 “Caffeine” overhaul (which focused on speed and integrating social network results into search) and that it affects “around 90% of searches”, there wasn’t much offered in terms of technical details."