Is the background position set at default center center?

On the site I'm using this great module on the image's focal point is at the left of the image - think of it as L-shapped: we need to have the image placed so that the "L" is consistently visible in the bottom left. When not using backstretch I can accomplish this with background-position: left bottom. When using backstretch, the left edge of the image goes off the viewport and the center center becomes the focus. Am I correct in my assumptions that that is the default setting for background-position with the module? Is there, or will there be an option to set the background position?

Thanks again, Matt!

k