I would be shocked if there isn't a head editor for every section of the New Yorker plus a head editor for the magazine plus several staff editors under each section.
When I worked in the newspaper business, you'd have copy editors to tidy up your prose, sub-editors to cut for length and style, and then the editors to decide what ran and where.
The author has been writing for the New Yorker for almost 20 years. He's probably pretty good on his own at this point, concussion or not :)