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A new site has a very specific link profile and link acquisition rate. The process of a new site gaining new inbound links is, where there is no outside SEO campaign involved, more like a process of accretion in that links are gradually added an the site goes through a few bursts of new inbound links.
Google has massively increased the number of changes they introduce for the past couple of years. Considering this, I don't think it would be that easy to tell the correct reasons for the OP's question, though he has given a detailed account of his new launch.
call it by its real name, "shuffling". Pure random shuffling designed to keep everyone guessing, bleeding and ad spending
...high CTR that can be also achieved through long time adwords ads (i monitor big brands in a certain industry that now ranking at top spots in organic results even for 1 word keyword because (?) of daily top spots in adwords)
(the main post is in the supporters section of the site here)
While a spiky rate of growth in the number of back links may be a factor used by search engine 125 to score documents, it may also signal an attempt to spam search engine....
I feel like we approached these by-the-book.