i dunno if i agree 100% with that, granted you are wiser than i regarding this...but don't you think the draw of man power and material defending the western front against the inevitable allied landing greatly weakened the eastern front, allowing the russians to advance and retake their soil?
seems like the germans had no problems marching thru western russia (occupation, of course, wasn't as successful) up untill moscow.
don't you think the extra man power required to guard the west could've given the germans that little push they needed to capture moscow?