It's all in consistancy. Keeping that basic "T" stance is one aspect. I'm wondering if you were perhaps dropping the bow arm a bit when shooting from the stand (common). Then maybe going back to the basic "T" form from the ground.

The book is very good and is a good read. I'm not sure how long you have been shooting so I can't really answer whether I think the book will be good for you.

I believe the book was designed for people who have been shooting a while and have pretty much leveled off in their improvement curve. The book was made to get you through to another learning level. It's also a great book for target panic.