You're right, I also have the problem with a xbox 360 controller. I already replied to someone in another thread that it might be a problem with a bad dead zone in the controller. Since then, I bought a new complete joystick to change the one on my old controller (which was actually fairly used and was a bit loose in the center), desoldered the old one, soldered the new one, and the problem is still there, when the controller is plugged the character in game is slightly strafing to the left continuously. I tried another more recent controller, and problem still occurs. A friend bought a completely new one, and problem still occurs.
I tried to calibrate the controllers in windows but problem is still the same. The character is always strafing slightly to the left.
The problem is not a bad dead zone in the controller. I tried the controller in multiple games like race simulation and so on, and there is absolutely no problem with the controller.
There is absolutely no settings in game regarding the dead zone of joysticks.