Monday, November 28, 2011

The Coors Field Hangover - Debunked (Part I)?

Coors Field has existed for 17 years. Born in the age of steroids Coors Field has never shaken it's past, even with the advent of the humidor. According to ESPN's ball park factors, Coors Field ranked third in runs scored in 2007 with a 1.16 factor or 16% more runs scored then at an average park (behind Fenway and Wrigley); 2008 Coors was third with a 1.126 factor (behind Chase and Ballpark in Arlington); 2009 Coors was first with a 1.247 factor; again in 2010 Coors was first with a 1.364 factor; and in 2011 Coors was second with a 1.347 factor (behind Ballpark in Arlington). Clearly Coors Field is still a place where runs are not a premium!  In the end, humidor or not, you can't add air and thus batted balls tend to travel 9% farther then at sea level (according to the Rox official website).

In addition to the ball traveling farther, giving the offense a boost, the pitchers have their own trouble because balls tend not to move as much in the thinner air.  So ultimately a perfect storm arrives when the ball and bat meet at home plate.  In the past, the Rox seemed to have the advantage when playing at Coors Field, where they have won more than 57% of their games from 1995 - 2010 versus 40% away.  In 2011 the opposite seemed true as opponents took advantage and Rox only finished 38-43 at home versus 35-46 on the road.  Over the years the effects of Coors Field has been debated especially in regards to a "hangover" effect that might exist when Rox return after a road trip.  My question then -- is there such a thing?

In this specific installment, I am looking at the games played from 2007 - 2011 (recent).  In future installments I will look at 2002 - 2006 (Gen R) and the 1995 - 2001 (pre-humidor).  To begin, is there a break in period for the offense when they return?  I have sorted through the Rox schedule and annotated games played since returning from a road trip.  First game back is Game 1 followed by Game 2 etc.  I then compiled each of the stats for "Game 1" and so forth.  Comparing these compiled stats should reveal the differences between the Rox offense when they first get home and after they adjust to the intricacies of Coors Field.  The graph below shows the average number of hits, walks, and strikeouts for all Game 1's (i.e. all Game 1 data during the season following a road trip) through Game 10.  Averages are used due to the fact that there were 59 Game 1's versus only 8 Game 10's.
Average number of hits, walks, and strikeouts for games after returning from a road trip
While both hits and strikeouts show a very small upward trend, the differences aren't overly dramatic. What is interesting is how Game 4 and Game 8 show a decrease.  Have to wonder if this isn't related to a new team coming into town and showing a different pitching philosophy (?).  Besides these average values what about percentages?  The graph below shows on base, slugging, and BABIP.
Percentages for games after returning from a road trip

Again nothing dramatic except for a Game 4 downturn in which slugging percentage seems to dive (this is a relative nose dive as the slugging percentage for Game 3s is 0.474 and Game 4s is 0.428 which over 50 games is about 3 bases!).  One has to wonder (and perhaps conclude) that not only do the Rox have to adjust but the team coming in does as well and whatever hangover might exist it is neither advantageous to the Rox or the opposition.  Although looking at the Win Loss column below it does appear Rox settle in and teams coming in later during a home stand are at a disadvantage.  Do note that Games 7 - 10 only amount to 69 total games of the 399 home games played after a road trip (Home games starting the season were not counted).
Winning percentage when returning from a road trip
To further coincide with my comment about both teams having a disadvantage when coming to Denver, the graph below includes not only the offense hits, walks, strikeouts (shown in the first graph above) but also now includes what the opposition is doing in sequential games.  It should be noted that the opposition's numbers are only for our pitching staff and not broken down by different team game numbers.  Eerily, hits and strikeouts are fairly consistent but Rox do show some advantage in the walk department.
Rox offense versus pitching when returning from a road trip
Overall the numbers don't appear to show a "hangover" effect when Rox return from a road trip.  Whatever effect exists seems to show up in both teams as they cope with the altitude.  While the raw numbers don't show that the Rox get comfortable, their winning percentage, the longer the home stand lasts seems to favor some sort of positive effect.

Part II will see if the length of the road trip plays a role in the Rox offense and pitching and whether flying east or west matters...

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