A lot has been written about the Google Sandbox effect, but much of it is based on early reports of what webmasters thought was a downgrading of a site that was just beginning to do well.
Many webmasters concluded from this drop that Google was giving their new sites some good rankings so other webmasters could find their content to link to it and then after a short period of good rankings for being a new site the rankings drop.
The theory was if the content was great that short period of good rankings would be enough to generate enough backlinks to give it a start on the journey to long term rankings in Google.

