The dearly departed (for the Pittsburgh Pirates, not the afterlife) Stuart Wallace has left a hole here at DSP. And I’m here to attempt to fill it. During the regular season I will address a situation or issue from a statistical point of view. The focus will still be the Nationals, but I plan to head out beyond the Nats from time to time. I may also veer into the fantasy sports world a bit more than Stuart did, but that’s where my knowledge is stronger. And some weeks I may just bring other important research to bear and comment on its potential effects.
Just a reminder that Stuart and I are not the same person. I’m not a neuroscientist. I’ve been to Nevada for about a total of one hour though I’ve probably spent more time in Las Vegas with Charlie Sheen than Stuart has anywhere in the world. I haven’t ever moonlighted though I have seen several episodes of Moonlighting. The one thing we do have in common is we are both former pitchers though my highlight is hitting the same left hander batter four times in the same game.
My first offseason submission heads off into the realm of fantasy baseball (tangentially), but is of use to all fans of baseball. The genesis of this column was a piece over at RotoGraphs by my colleague Brett Talley. Specifically, his inclusion of Justin Upton and the initial comment on the article noting that if you overlay Upton’s home runs from 2014 each and every one would have been out of Petco Park. Can we use this tool in the manner suggested? If we do, what issues should we be aware of and how should we compensate for these issues.
Hit Tracker/ESPN Home Run Tracker Background
In 2005, Greg Rybarczyk’s created Hit Tracker. More recently, the site was assimilated into ESPN when Mr. Rybarczyk and ESPN began working together. The stats and graphics you will see below are courtesy of ESPN Stats & Information Group and can be found here.
The site is full of wonderful data focused on HRs hit and HRs given up. The data runs back to 2006. Also included on the site, is a glossary to help new users understand the stats. Today, I’m going to focus on one of the simpler tools on the site – park overlays.
Using Park Overlays to estimate home runs in new home parks
Whenever a player is traded to a new team or signed as a free agent, one of the first things many people do is head over to HitTracker and check to see if the HRs he hit last year would have been HRs in his new park. Why? Because it’s fun and easy.
So, here is an image of Justin Upton’s HRs from 2014:
Upton was third in the NL in HRs with 29 last year. According to HitTracker, Upton had two lucky home runs, eight just enough home runs, and six no doubts. Every other home run (the remaining 13) falls into the catch-all category plenty.
Now, let’s overlay his HRs in 2014 as if all of them were hit at Petco Park.
The red line represents Petco’s fences. Perfect! Not a single HR wouldn’t have left the yard in Petco. And Petco is really a tough hitters’ park. All of my friends say so. There shouldn’t be any issue with Upton moving to San Diego. I assume he’ll hit at least 29 HRs again next year. A.J. Preller is a genius.
For fun, let’s take a look at how far those balls would have gone in Coors – a launching pad if there ever was one. I can’t imagine how this graphic will look.
Hmm…this thing must be broken. Two of Upton’s HRs wouldn’t have cleared the fence in Coors Field and three more look like they may or may not have been HRs at all. In Coors? How is that possible – everyone hits HRs in Coors.
It’s not just the dimensions. The dimensions matter, obviously, but deep fences don’t automatically make a pitcher’s park and short porches don’t always favor hitters. In addition to the dimensions, the weather matters, the air density/quality matters, and topology of the surrounding area matters. The ball tends to travel better in warm air and thin air, and the surrounding buildings and ballpark structures can influence how well the ball carries.
As Weinberg notes, Petco has a marine layer of air that keeps the ball from traveling quite as far as it would in “normal” atmosphere.
While the changes to Petco Park in San Diego and Safeco Field in Seattle will make a some difference in home runs, it doesn’t change the nature of the air surrounding those parks. As Coors Field in Colorado demonstrates, it doesn’t matter how big you make your park when the air that fills it offers so little in the way of resistance. The ballparks of the West Coast all benefit from the heavy marine air which drifts in, suppressing offense for night games in particular. Making a park bigger or smaller plays a relatively minor role.
Finally, as Weinberg notes in his piece, the surrounding building and ballparks structures play a role. Too often changes to the park’s infrastructure play a role. Perhaps the most famous in recent memory is the addition of the 600 Club at Fenway Park and the subsequent change in wind patterns. Also, recent changes to Globe Life Park in Arlington have made the Texas Rangers’ home ballpark closer to neutral than hitter friendly.
From Robert K. Adair’s groundbreaking book The Physics of Baseball, he identified a number of factors which affect fly ball distances. I’ve listed them below.
|1000 feet of altitude||adds 7 feet|
|10 degrees of air temp||adds 4 feet|
|10 degrees of ball temp||adds 4 feet|
|1 inch drop in barometric pressure||adds 6 feet|
|1 mph following wind||adds 3 feet|
|Ball at 100% humidity||subtracts 30 feet|
|Pitch thrown +5 mph||adds 3.5 feet|
|Hit along foul line||adds 11 feet|
|Aluminum bat||adds 30 feet|
I will leave you with one more example – this one from one of 2013’s highest profile free agent signings – Robinson Cano. Cano hit 27 HRs in 2013 for the Yankees. He entered free agency with great expectations and was signed by the Seattle Mariners.
Here is a picture of his 2013 HRs with no park overlay.
And those same 2013 HRs overlaid against Safeco’s dimensions.
It looks like only one HR was “on the fence” after the overlay. There was some concern of his move to a less friendly hitters’ par, but the belief was that Cano’s power shouldn’t be greatly affected. We all know what happened in 2014 as Cano’s HR output fizzled to 14 — his lowest HR total since 2009 when he hit 25. His drop in HRs may not have been caused completely by his new home, but it certainly contributed to the power outage.
Park effects come in all shapes and sizes, visible and invisible. In the end, it may not have been Robinson Cano’s new contract weighing him down in Seattle, but that cool West Coast air.