I have encountered a serious problem with google rankings and the sequence of events goes like this for a high volume phrase.
I make changes to the page which gets a score of 98 in Moz and equally good scores in other tools.
I resubmit the page to Google for searching via crawl in google webmasters.
After about 1/2 to 1 day, the page will be ranked between 30 and 50.
Within another 1/2 to 1 day, the ranking goes completely away.
This page has much higher scores than pages that are ranked. Other phrases continue to rank OK.
