One criticism of the Phillies' offense last year that I've occasionally come across is that the team couldn't hit on the road compared to its performance in the cozy confines of CBP. Some of the numbers bear this out, particularly the team's slugging performance on the road (numbers are ranks among NL teams in 2005):
So did the Phillies collectively choke on the road? Were the hotels they stayed at away from home to blame? Or were they the victim of something else?
Everyone knows that at home the Phils' offense enjoyed the small dimensions of CBP. Using park factors from Baseball Think Factory's Dan Szymborski, we can see that CBP increases overall scoring by about 10% (a lot indeed, but not nearly as much as the media or certain pitchers made it out to increase scoring). Almost all of the scoring increase comes from CBP's inflation of home runs; the park is only slightly favorable to all other hitting events, but does increase home runs by 16%.
To look into the disparity in home and away performance, I've calculated road park factors for each team. A team's road park factor is a measure of the team's park factor for the parks it visits on the road, weighted by the number of games played at that park. (If I had endless time, I'd weight the road park factors by innings played in the parks, but the rougher calculation of games played is going to be good enough for our purposes.) In other words, the road park factor is a sum of the park factors for each away game's park, divided by 81 (the number of away games over the course of the season).
It's a mistake to assume that every team will have the same road park factor or that road park factors will all be 1 (neutral). Take Colorado, for instance. Colorado is the most extreme hitters' park in the majors, by far. Every other National League team gets to play at Colorado, but the Rockies don't. And, the NL West teams get to play at Colorado 9 or 10 times, which is 9 or 10 times more than Colorado does, and about 6 times more than other NL teams do. Thus, Colorado will have a much lower road park factor than all other NL teams, and the NL West teams' road park factors will get a benefit other NL teams don't.
The Phillies are in a unique position as well. Their park isn't as extreme as Colorado's, but when the Phils hit the road in their division, they have to play in two of the most extreme pitchers' parks in baseball (Washington and Florida), one slight pitchers' park (New York), and one slight hitters' park (Atlanta). Thus, the Phils' road park factor is going to be lowered by not playing any games at CBP on the road as well as by the 18 games they played at Washington and Florida. And, in 2005, the Phils' number was lowered even more by playing their interleague road games in a neutral park (Oakland), a pitchers' park (Baltimore), and an extreme pitchers' park (Seattle).
A look at the NL road park factors bears this out, with the Phillies and Colorado at the bottom of the list:
The difference from neutral in this chart isn't that significant, as the Phils only suffered a 2.5% decrease from neutral in their road park factor. However, comparing the road park factor to neutral isn't the real measure of the differences noted in the beginning of this piece. Rather, what we need to look at is the difference between the Phils' home and road park factors, because only that measure will show us the true nature of the obstacle the Phils face when their home and away stats are compared. By this measure, comparing the home and road park factors, the Phils faced away parks that decreased run scoring by 12.5% compared to CBP, the second-most-depressed comparative road run scoring environment in the NL:
The chart at the beginning of this article shows that the real problem with the Phils' road offense was in the power numbers. It's undeniable that the team had a severe power shortage on the road compared to at home. However, we can look to road park factors to see if that is completely explainable by the parks the Phils visited in 2005. Not surprisingly given the other parks in the NL East and not visiting CBP, the Phils faced the most home run deflating road schedule of any NL team:
And, compared to the conditions the Phils had to play with at home, the difference in home and away home run park factors meant the Phils had a 20.9% decrease in home run environment on the road, second to last (again) to Colorado:
How do these park factor differences compare to the actual decreases the Phils suffered on the road in 2005? The Phils scored 427 runs at home compared to 380 on the road. That's an 11% decrease, just a bit better than the predicted 12.5% decrease based on the parks they visited. The Phils hit 94 home runs at home but only 73 home runs on the road. That's a 22.3% decrease, only slightly higher than the predicted 20.9% decrease based on the parks they visited. Basically, the road park factors are almost perfectly in line with the decrease in offense the Phils had on the road in 2005.
The conclusion is pretty obvious: on the road last year, the Phils were victims of nothing other than road park factors. As long as CBP stays the same in terms of inflating runs and home runs and the other NL East stadiums stay the same in decreasing them, we can expect more of the same in the future.
If you're looking for them, AL road park factors (for runs, home runs, and comparatives for both) are below: