Hello,
unfortunately I cant definitely say if the problem existed before any mesa or PoE. I did't use PoE too much on Linux, because I was too lazy to set up a manual sync until recently. As far as I can recall, I didnt have any problems before the 3.0 patch. But take this with a grain of salt.
Yesterday the game started fine multiple times. However today it wont start after resuming from hibernate and restarting steam. As mentioned previously the game wont even generate the Player.log file.
Here is the link to the the log from yesterday, when the game did run. Maybe it will be of some help: http://pastebin.com/yeV0Uehw