If you read through the entire NYT review of The Happenning, it ends pretty negatively. Since the ending is pretty much summing up the whole film, I would think that would affect the final review score that Metacritic comes up with more than the initial more flattering comments.

A Metacritic score has never so directly disagreed with a review's content, IMO, since I started visiting this site as its inception, and I think it would be wise to review the score you came up with.