Jamie Garcia struck out Ryan Howard in the second inning of Game 3, bringing up what could be the Phichillies' heel: left-handed pitching. The difference isn't super-dramatic, but there's a difference, as you'd expect:
Ryan Howard is neutered by left-handed pitching, and while John Mayberry, Jr. helps negate that disadvantage, it's a pretty big deal to lose four at-bats of the good Howard. Chase Utley doesn't have any platoon splits at all, so that's a non-factor.
There are other important splits, too. It turns out that Cole Hamels does really well against hitters with a helmet, and his splits are great against hitters who use a cylindrical wooden object to attempt to strike the baseball after it's thrown, so look out for both of those.