Python Matplotlib Radar not correctly centered
Seems to me that fig.add_axes() is miscalculating the dimensions here, essentially doubling the "left" and "bottom" values, not sure why. So you should use 0.8 for "right" and "top" values, as in: 

axes = [fig.add_axes([0.1, 0.1, .8, .8], polar=True,
            label="axes{}".format(i))
            for i in range(len(variables))]