Andy Pettitte allows more home runs at home than on the road since the new Yankee Stadium opened in 2009. The biggest reason is that right-handed batters can take him deep the opposite way in The Bronx.
As you can see, it's rare for right-handed batters to go deep the other way against Andy on the road. At home it's a different matter.
If a Rangers hitter goes deep the other way against Pettitte Monday night, you can blame the stadium.