If I were to put on my conspiracy theorists hat, It could be publishers themselves posting bad reviews to drive down the metacritic score. Both of those games are now several weeks past their initial release window. From a publisher view point the majority of sales have likely been made. If they owe money to the developer based on a score, they could drive the score down pay the developer for the lower score then delete their comments and restore the score. Seems like an easy way to anonymously save some funds.