An excerpt from my blog:

"Recently, Padres General Manager Jed Hoyer spoke, during an interview with AM 1090's Darren Smith, about the psychological effect that Petco Park has on the San Diego Padres:

It seems like we don't have the same approach or confidence at home...[it] is a challenge and I do think we need to approach the mental side as well as the physical side [because] we swing with more confidence on the road.

Jed isn't stating anything Padres fans haven't heard before. Padres and opponents alike have made numerous comments about the psychological effect of Petco Park: 

When we get on that plane out of San Diego, every hitter is a happy hitter. - Adrian Gonzalez 

The more I try to figure [it] out, the bigger headache I get. - Phil Nevin 

It isn't anything new that Petco Park stifles offensive production -- a cursory look at ballpark factors or team run totals proves this point quite well -- and for those who follow the Padres, it's nothing new to hear the team talk about the "mental" aspect of playing at Petco Park. 

However, whether or not the psychological aspect actually translates into a disproportionately poor result at home is yet to be shown."

The rest can be read here: http://fedupfriarfans.blogspot.com/