Billingsley will get to pitch half his games at Dodger Stadium while Hamels starts half his games at Citizens Bank Park. Not claiming to be an expert on either Hamels or Billingsley, park factor is enough for me as it's the only thing I'm sure of.
Ok, I'm pretty new at this, and I really don't know too much about major league parks (I'm a fantasy football guy). So, which of these stadiums are pitchers parks, Dodger or Citizens? I know that wherever Washington plays is a pitcher's park. What other stadiums are considered pitchers parks? Sorry for the ignorance.
Actually, Washington plays in a football stadium, but that's another story.
Here's a link
that tracks park factor for the season through this week. Basically, the more a park factor number is above 1.0, the more a hitter is favored in that particular statistic. The more the park factor number is below 1.0, the more a pitcher is favored in that particular statistic.
As a few stadiums made changes to their outfield this offseason, I'd go with the article I'm linking to rather than the historic numbers. Beware the smaller sample size though.