In an After Hours Webmaster Hangout, Google’s John Mueller answered multiple questions about what kinds of changes may impact rankings and what kinds of changes will not.
Along the way Mueller explains different scenarios that are harmless and also the kinds of changes that may impact how Google sees the website, including seeing it as a brand new site.
Search Performance Impacted by a Site Revamp
The person asking the question said that the last three sites he had “revamped” had experienced extremely negative ranking changes in Google search.