I have noticed in a couple of my leagues that the chat window opening by default on the league landing page is creating "spoilers" for coaches who want to hide their game results until after they have watched the game. Because the chat window is immediately visible, it's hard to ignore at least the first few lines of chatter, which could reveal the outcome of the game that coach wanted to watch first without knowing its eventual result.
I think it depends on the league. Some private leagues the chat window is great but i do agree it should be a movable dock cause i find it annoying in the spot it's in. Also a great idea to be able to have a setting to keep it off for those who don't like it. I think the overall idea has worked but there just needs to be some more customization with it to make it work for everyone :)