So after much speculation the Diamondbacks announced today that they will be introducing a humidor at Chase Field in time for opening day. Everyone is scrabbling around to try to understand how this will impact the run scoring environment there but the cold hard truth is that nobody really knows. Will there be a change reminiscent of Coors Field when they introduced a humidor? Will Phoenix become a pitcher-friendly park? The answer to both of these questions will be answered properly further on down the road, but we can make some decent early projections. Or can we?
The problem is that we only really have the park factors at Coors Field to go by, from before the humidor and after. This is the most helpful data we have but unfortunately even this doesn’t actually help us that much, because the significant difference in altitude (Coors Field is 5,183 ft above sea level, Chase Field is 1,082 ft) makes the two situations incomparable. Also the climate is so different that it is difficult to extrapolate the effects from one to the other.
That said, if we were to use the Coors comparison to inform our thinking, what do the historical park factors tell us? Well, in a brilliant article on Fangraphs, Jeff Sullivan crunched the numbers and found out that the impact of the humidor being introduced at Coors was a 15% reduction in home runs and runs scored. 15% is is pretty significant. To put that 15% into context, if Giancarlo Stanton had hit 15% more home runs last year he would have hit 68 instead of 59. Or 15% fewer home runs would have been just 50. Big differences indeed.
Of course the Stanton comparison is just for context. Nobody’s individual numbers will be so significantly impacted, not even D-backs hitters, as they only play half their games in Phoenix anyway. It will hurt some guys numbers though. Run some stats through the new park factors and Paul Goldschmidt only scores 33 homers last year instead of 36. Jake Lamb hits 27 instead of 30. And what about players in the NL West who play regularly throughout the season at Chase Field? Chris Taylor, Trevor Story and Wil Myers all hit 3 homers there last year. Visiting players will be impacted by the humidor for sure.
And what if we are not overestimating the effects, but underestimating? Physicist Alan Nathan’s study published in The Hardball Times predicted that the humidor could suppress home runs by up to 50%!
Whilst it is clear that we don’t, and won’t for sometime know with any precision the impact the humidor will have, all signs point to it having a beneficial impact for pitchers and a negative impact for hitters. It won’t be as pitcher-friendly as AT&T Park but it certainly makes me re-evaluate Zack Greinke, Robbie Ray, Zack Godley and Taijuan Walker for my fantasy drafts!
Steve K – @kleinst01