Welcome to Philadelphia Cliff. Now here's one piece of advice: don't believe what you hear about Citizens Bank Park. It's a slightly hitters-friendly ballpark, and has been for a while now. But, it's not the bandbox it once was and that the media still believes it is.
Still, it's a very different stadium than your previous home stadium - Progressive (Jacobs) Field. In fact, even though CBP isn't a bandbox, it might seem like one in comparison.
Although not the best park factors out there, ESPN's are the most readily available in season. Here's how the two stadia compare so far this year. Numbers above 1.00 indicate the park increases that stat; numbers below 1.00 indicate a decrease:
Lee's previous home park decreased run scoring by 16% whereas now he'll be pitching somewhere that increases it by 6%. CBP increases homeruns only by 7%, but that's almost 40% more than Progressive. The other drastic difference is in triples, where CBP increases them by 7%, but 52% more than Progressive.
Lee's career home/road splits indicate he's taken advantage of Progressive. His career home ERA is 3.80, whereas his career away ERA is 4.22 Last year's Cy Young campaign showed the same thing -- 2.45 at home versus 2.61 on the road. But his career WHIP is actually better on the road - 1.31 compared to 1.32.
It's hard to imagine that Lee won't feel the effects of CBP compared to Progressive. However, with the change in offense behind him, the park change likely won't matter in the results of games.