Quickly run upstairs and try to avoid the brawler. Take out the auger to protect yourself from their bullets, or use the Marksman secondary ability. You can run towards the offices on the left and right, but be careful, the brawler can smash through the walls.
You can also run straight to the Chimera on top and once killed, stay there. Shoow the brawler (tag and shoot with the bullseye) and keep moving. If you keep moving in a circle, the brawler will keep following you and probably won't get close.
__________________
__________________
|