Is this chart rotten?

Some students pointed me to a FiveThirtyEight article about Rotten Tomatoes scores that contain the following chart: (link to original)

This is a chart that makes my head spin. Too much is going on, and all the variables in the plot are tangled with each other. Even after looking at it for a while, I still don't understand how the author looked at the above and drew this conclusion:

"Movies that end up in the top tier miss a step ahead of their release, mediocre movies stumble, and the bottom tiers fall down an elevator shaft."

(Here is the article. It's a great concept but a bit disappointing analysis coming from Nate Silver's site. I have written features for them before so I know they ask good questions. Maybe they should apply the same level of rigor in editing feature writers to editing staff writers.)