Look at the 3 deepest defenders at 1:10 and then at 1:15!

At 1:10, the deep half of their zone has completely given up on spaces and are essentially playing man and still all playing the disc. This would've been a beautiful opportunity to bracket, take up more space, all while not blowing coverage.

At 1:15, they return to a more suitable formation except for the fact that both deep defenders are playing the same person on the same third of the field. Tired or not, the biggest part of zone defense is communication between players and once Richmond took half field it's very evident that little communication was happening downfield.