When Joe Girardi  announced his rotation for the ALCS, Andy Pettitte  and Phil Hughes  had been flip-flopped, with Hughes now taking the ball in Game 2 and Pettitte going in Game 3. Girardi cited a variety of factors, but no doubt one of the numbers he consulted was Hughes’ home/road splits. Over his career, and continuing this year, Hughes has performed significantly better on the road than he has in New York, especially in terms of home run prevention.
This shouldn’t be all that surprising, given that Hughes is an extreme fly-ball pitcher and New Yankee Stadium is home run-friendly, especially for left-handed hitters. He’s the kind of pitcher who will be hurt most by how the park plays, and that shows up in the results. Getting him a start on the road in Game 2 seems like a good idea. But a closer look at the data suggests that this is a meaningless move.
The Ballpark in Arlington is actually a very similar offensive environment to New Yankee Stadium. Both parks are left-handed-power-friendly, increasing home runs by 24 percent (New York) and 18 percent (Texas). They’re not as nice to right-handed power hitters, though both are still above average in terms of inflating home run totals, with right-handed bats getting a 10 percent boost in New Yankee Stadium versus the five percent boost they get in Texas.
Phil Hughes home/road splits
Park BB/9 K/9 HR/9 FIP Home 3.28 7.72 1.43 4.58 Road 3.05 8.05 0.67 3.44
A park doesn’t just influence home runs, however, and this is where the benefit to starting Hughes in Texas begins to break down. New Yankee Stadium promotes home runs at the expense of doubles and triples, both of which occur at a lower-than-average rate in that park. In Texas, home runs are inflated, but so are doubles and triples, so offensive levels overall are higher.
By attempting to take advantage of Hughes’ road numbers, the Yankees are actually asking him to pitch in an even tougher environment than the one he faces in New York. Someone has to pitch the games in Texas, but they didn’t make Hughes’ job any easier, and they shouldn’t expect him to match his career road numbers just because he gets a start outside of the Bronx.
Over in the National League, the San Francisco Giants did the same switcheroo, swapping Game 2 and Game 3 starters from the NLDS so Jonathan Sanchez  would start in Philadelphia and Matt Cain  would start in San Francisco. This time, the numbers suggest it could make a pretty significant difference, as it would be hard to find two less similar parks than Citizens Bank Park in Philadelphia and AT&T Park in San Francisco.
Sanchez will now take the hill in a park that is very home run-friendly, creating 16 percent more home runs for left-handed batters and 20 percent more for right-handed hitters. However, Sanchez is the type of pitcher that is least affected by the environment in which he’s pitching, because a large percentage of his at-bats end with a walk or a strikeout. This year, 38 percent of the batters who stepped in against Sanchez failed to put the ball in play. Only 27 percent of the batters that faced Matt Cain did the same.
Sanchez’s high-walk, high-strikeout approach makes him a more suitable choice for parks that inflate run scoring, as Citizens Bank Park does. Meanwhile, AT&T Park works perfectly with Matt Cain’s skill set.
Cain, like Hughes, is an extreme fly-ball pitcher. San Francisco is one of the hardest places to hit a home run, and is most challenging for left-handed batters. The ballpark depresses home runs by lefties by 18 percent, making it the perfect place for a fly-balling right-hander like Cain to go up against Chase Utley , Ryan Howard  and Raul Ibanez . The big alleys do increase doubles and triples, so it plays as a mostly fair offensive environment overall, but it’s certainly a better place to ask Cain to challenge the big left-handed bats in Philadelphia’s lineup.
Both Joe Girardi and Bruce Bochy  have changed up their rotations to try to optimize their outcomes in their respective league championship series. The Giants’ switch could pay real dividends, as they are able to take advantage of the unique way each park plays. But the Yankees are just going to have to pitch well, because the two parks the ALCS will happen in are too similar to really exploit any matchup differences.