User blog comment:Shadowunleashed13/Sonic Boom is out now in North America!/@comment-15134203-20141111211642/@comment-24768952-20141112033449

Or maybe they saw from other people's gameplays, (those who already got the game) and they may have found out how bad it was...

...Another reason was that SEGA denied further advance review copies of both games.

IDK if this answers your question.