jollydodger
A-giving the road team balls that are different in any way is unethical
B-I'm certain they're doing it, and I'm certain EVERY team would do it in the same situation
C-while it is unethical, I cannot blame them
D-this isn't something that everyone in the organization would need to know about, and thus, could easily be kept quiet
E-I dont think poorly of the Rox for probably doing this, as I said, everyone else would too
F-Go Dodgers!
12:32 AM Oct 26th

evanecurb
We could hit .300 at Coors if we played for the Rockies. Not when we were playing. Today. at age 65. We could do that. For real.

Signed,

Steve Whitaker
Horace Clarke
Roger Repoz
Reuben Amaro, Sr.
Jake Gibbs
Bobby Cox
Charlie Smith

10:55 AM Oct 11th

MarisFan61
OK.....looking FORWARD, how about a challenge.

Not to the Rockies, but to the doubters here. :-)

What would it take about the Rockies' performance next year (or ever) for you to be convinced?

Looking at "the difference of the differences" (Dave's great phrase), we saw how extremely the Rockies hitters became transformed this year at home compared to on-the-road (while their opponents' hitting increased just a tiny amount).
As I put it, basically Steve Whitaker becoming Henry Aaron.

If next year (presumably under a more airtight system of handling the balls) they go only from Steve Whitaker to Horace Clarke, will that be enough?

What would it take?

Here's what it would take to bring me into your "doubter" camp: Next year's data being anywhere close to this year's.
3:24 PM Oct 4th

Richie
If I were going to set up a conspiracy, I sure wouldn't let bat boys in on it.
1:09 PM Oct 2nd

MarisFan61
re Ben Jedlovec: But that wouldn't explain the Rockies HUGE difference between their "road" and "home" hitting this year.

I posted the data (as of a few days ago). As I said, it was like being Steve Whitaker becoming Henry Aaron (just about).

Forget everything else; just look at that.
Is it plausible in the least?

Sometimes our gut can do most of the work. :-)
1:59 PM Sep 29th

stevebogus
Rule 3.01 covers the pre-game duties of the umpire(s). I have found two somewhat different versions of the rule at MLB.com

3.01 Before the game begins the umpire shall-

(c) Receive from the home club a supply of regulation baseballs, the number and make to be certified to the home club by the league president. The umpire shall inspect the baseballs and ensure they are regulation baseballs and that they are properly rubbed so that the gloss is removed. The umpire shall be the sole judge of the fitness of the balls to be used in the game.

or this version (which was changed to the above in 2007)

(c) Receive from the home club a supply of regulation baseballs, the number and make to be certified to the home club by the Office of the Commissioner. Each ball shall be enclosed in a sealed package bearing the signature of the Commissioner of Baseball, and the seal shall not be broken until just prior to game time when the umpire shall open each package to inspect the ball and remove its gloss. The umpire shall be the sole judge of the fitness of the balls to be used in the game.


Could the home team pull a switcheroo during the game? I don't know if there are any security measures to prevent a substitution while the umpire is busy working the game. What happens to the baseballs after the umpires inspection?

My issue with the conspiracy theory angle is 70 or 80 games is NOT a big enough sample to prove anything funny is going on. Rockies slugging around .500 in Colorado? that isn't much different from 2009 (.483) or 2007 (.480). Rockies slugging just .350-ish in away games? Look at 2005 (.359). In 2010 the difference is a bit larger, but does that really mean anything, or is it just chance? Carlos Gonzalez is having a breakout season, but is doing so with an enormous home/away split. He's hitting well on the road (.293/.327/.459) but is a monster in Colorado (.386/.432/.755). We've seen that before in Colorado, haven't we? He is responsible for a good chunk of the difference. The Rockies also have some players who aren't hitting at all in road games this season. Miguel Olivo (.211/.276/.322), Seth Smith (.211/.282/.357), and Dexter Fowler (.193/.285/.259) have been horrible on the road while doing well in Colorado. Those road stats do not represent their true abilities. And that is the entire problem with "normalization" of stats based on a half-season of data. It takes a while for the sample size to get large enough to be reliable.


8:33 PM Sep 28th

MarisFan61
P.S. A couple of things:
I'm afraid I made my obligatory "typo": At the end there, it's supposed to be, "....couldn't POSSIBLY be that clear....."

And also:
Dave, I posted some of your proposed explanation on that Yankee site (with attribution). I assume you won't mind.
3:19 AM Sep 28th

DaveFleming
Well...who brings the baseballs out to the homeplate umpire? I always thought it was the batboy. And he usually brings the balls out bwtween innings, right? So he brings out the humidor balls when it's a Rockies pitcher on the hill, and the non-humidor balls out when the visitors are pitching.

Even if there is one giant bag of game-baseballs, you could pull it off. Just load the humidor-saturated baseballs in first, and put dry balls over them. Then tell the batboy to take baseballs from the bottom of the bag when the visitors are due to bat.

It's not a perfect system, but it would give the Rockies an advantage.
10:34 PM Sep 27th

chuck
I just was looking at this question this week. I used home runs per batted ball. From 1995 through 2001, the average hr/batted ball rate in Coors was 5.23%. From 2002-2004 it was 4.77%. From 2005 to 2009: 3.72%.
So in the first humidor years homers dropped by 9%. In the 2005-09 period they dropped 22% from the prior humidor years, and this represented a 29% drop from the pre-humidor times. The bigger change was in 2005.

I think the Rockies instituted the humidor to address the problem of attracting good pitchers to play for them. In 2005 they tried something different- perhaps leaving balls in the humidor longer. This baseball prospectus article alludes to this. See paragraph six:
http://www.baseballprospectus.com/article.php?articleid=5386
They also apparently started letting the grass grow higher, affecting ops, though not homers.

Here’s a theory: seeing the dramatic results, what they may have started doing recently was to have two bags of baseballs- one humidored longer than the other. This way they could deny having one non-humidored bag for opponents. If Bill Veeck was around now, he’d applaud the idea.

Here’s a variation on what you did, Dave. Let’s take the the Rockies’ vs opponents at home index and compare it to the Rockies vs opponents on the road.
So for 2002, at home the Rockies’ hr rate per batted ball was 4.13%; their opponents were at 5.56%.
4.13/5.56 gives an index of 74. Doing the same for away games, that index is 65.
Here are those indexes since 2002:

year coors away
2002 74 / 65
2003 105 / 112
2004 110 / 109
2005 107 / 73
2006 85 / 136
2007 133 / 82
2008 123 / 104
2009 138 / 144
2010 152 / 104

The Coors advantage this year, 152, is the largest in the history of the park, and we’ll have to see if this repeats itself next season.
So this year does show a very large difference between how the Rockies outhomer their opponents at home in contrast to away games. And there was a similarly large difference in 2007. But one also sees the opposite- their opponents having a much bigger advantage in Coors in 2006. But I think 2006 was more about the Rockies’ pitchers doing a great job on the road that year, limiting opponents to a 2.74% rate.

Let’s look at it a different way.
Opponents’ home run rate, average since 2005:
3.30% in their home parks
3.42% in Coors

Rockies’ home run rate, average since 2005:
3.44% in opponents’ parks
4.16% in Coors.
This disparity starts showing up in 2007. In 2005-06, their average in Coors was 3.47%. From 2007, the Rockies home run rate has topped 4% at home each season and is close to 5% this year. Their home average from 2007-2010 is 4.51%.

Since 2007, the Rockies outhomered opponents on the road 3.48% to 3.23%, an index of 108. In Coors they've outhomered opponents 4.51% to 3.31%, an index of 136.

Supporting the idea of humidoring balls for different amounts of time: the Rockies’ homer rate in Coors so far this season is 4.94% per batted ball. This is a similar rate to that seen in 2003 (4.95%) and 2004 (4.85%) in the early humidor period. It’s the highest rate seen since 2003. Their opponents’ rate in Coors this season is 3.26%, which is consistent with the lower rates seen since 2005.
It’s hard to keep people silent in a conspiracy. If there are more than a couple people involved in a plot like this, it’ll come out eventually.


2:31 PM Sep 27th

SeanKates
It's especially hard to win as a one-sided park factor team in that division. Arizona is also extremely hitter-friendly, but the three remaining stadia are very pitcher slanted. 60% of the in-division games should favor teams that take advantage of a pitcher friendly park...leaving the Rockies and the Diamondbacks in a conundrum for roster management. That was one of the stated reasons for moving to the humidor, as well as the ability to draw FA pitchers. Of course, the Rockies have done almost NONE of the latter in the humidor period, so who knows how true or fair the first reason was either.
8:15 AM Sep 27th