The Arizona Diamondbacks have a problem. They hit too many home runs — and so do their opponents. Nice problem to have, right? If you want baseball to be fair across stadiums, not really.
The air is very dry in Phoenix. At Chase Field, the Arizona Diamondbacks home turf, that translates into more home runs. Drying out baseballs makes them more bouncy — they launch off the side of a bat with more intensity than at other stadiums.
To combat the effect, the Diamondbacks have purchased a humidor, according to the blog Inside the ‘Zona. A humidor triggers stereotypical images of Cuban cigars and smoky rooms, but this humidor is more than a box. It’s basically a refrigerator, except it also maintains a constant humidity. The Colorado Rockies have been using one for 15 years.
Just like the Rockies, the Diamondbacks will set their humidor to 70 degrees and 50 percent humidity. For those keeping score, that’s a dew point of roughly 50 degrees. I love it when the math is simple.
That is a stark increase in air moisture compared with what these balls are typically stored in. Just look at the forecast for Phoenix on Monday — the temperature is going to be 88 degrees and the dew point will be a parching 22 degrees at 7 p.m. Put those figures together in the ol’ humidity calculator and you get a whopping 9 percent.
No doubt about it — the Diamondbacks’ baseballs need to absorb some moisture, particularly if they want their stadium conditions to be comparable to others in the league.
The science of mushy baseballs is pretty intuitive. Imagine taking a dry, round sponge and throwing it at the wall. It bounces off the wall and maybe again off the floor and then rolls to a stop in the corner. Now, get that sponge a little wet and do the same thing. Splat, right? Not so bouncy.
Another (kind of bad) analogy is a fully inflated basketball vs. one that’s lost some air. Moisture in a baseball has the same effect as releasing air from a basketball.
Inside, which has been lobbying for a humidor for a long time, explains how this is going to affect play at Chase Field:
- The ball weighs more, so distance is reduced when balls are put into play, and
- Because balls are relatively “wetter,” they become “mushier” upon impact, reducing the amount of force transferred to the ball from the bat, and
- Pitchers should have a better grip on the baseball, helping induce more spin
If you’re still skeptical humidity can truly change the outcome of a baseball game, you should crunch the numbers.
Using a “cheating in baseball” study from researchers at the University of Illinois, Inside calculated how the new squishy wet baseballs would affect the home run figure at Chase Field. They took the 2013 home run number — 146 — and reduced it by 37 percent (plus or minus 6.5 percent for error). That would be somewhere between 82 and 101 home runs in 2013. It’s a major change.
Thought about in another way, small changes in humidity can effectively change the distance of the outfield fence. Beyondtheboxscore.com published a nice chart in 2014 that shows the differences in effective home run distance when you factor in humidity.
There are a lot of different ways to slice this pie, but the results will be the same. Once the humidor is installed at Chase Field, epic home run tallies will be a thing of the past.