Keeler: Johnson's number one enemy is himself

Sean Keeler of The Des Moines Register wrote an interesting column earlier today about what Zach Johnson will be up against when he defends at Augusta National next week.  Keeler argues:

For Zach Johnson, the No. 1 enemy at Augusta National this week is not the heathen media. It's not the tweak at the tee on No. 1. It's not the new green on No. 7.  It's himself.

If I had to pick the menu for the Champions Dinner, I'd be nervous too.