The Seattle Seahawks have to trim their roster to 53 players by August 26 at 1 pm PT. While this is partly a time for 12s to be excited because the season is getting really close, the reality is that it means a lot of people will be losing their jobs. That's not fun.
Seattle has a recent history of not making a lot of moves until after the deadline is done. When Pete Carroll was running the team (yes, he was the head coach, but he was also the vice president of football operations), the team often didn't announce its roster until a couple of hours after other teams.