Just repeating what I saw someone else say, it might be because Grayson sees balls over the top of our defence as a problem and it reduces that risk as there's not as much space for it. Also if we're going to be playing a defend from the front pressing game there's less ground for Vaughan to cover which will add up over a long season.
Probably wouldn't have helped us because our only gameplan was to play the ball over the top to Defoe so we'd have been shooting ourselves in the foot. We seem to have a few avenues for attacking now, I'm liking all the crosses going in. Worked with Allardyce but never seemed to occur to Moyes.
I liked the fact Grayson has thought outside of the box. Obviously cant be proved either way whether it has/will work but at least he's trying something.
Should have been done years ago, teams have consistently been exploiting space on that pitch and embarrassing us in the process.