It often seems that the great back nine after a mediocre front is a result of just relaxing or not caring so much about the results, at least for me. Many of us play better when we create less internal mental stress. On the flip side, the poor back nine that follows a nice front, for me, often is a result of getting too wrapped up in results. With each poor hole on the back nine, I see a nice round slipping away, which increases my internal stress and leads to even shakier play. When I am at my best, it is one shot at a time without a concern over the final result of the round. Doesn't happen enough.