The? Atlanta Braves?play their first game in their new home, SunTrust Park, on Friday night as they host the San Diego Padres. It almost seems like yesterday that the Braves were moving from Atlanta-Fulton County Stadium, one of those multipurpose monstrosities that were built in the 1960s, to Turner Field, a baseball-only park that was converted from its original design as the main stadium for the 1996 Olympics. But that was 20 years ago, and in a multibillion dollar industry, stadiums don't have the same life span as the Colosseum that Roman gladiators fought in two millennia ago.
With the opening of a new ballpark, one of the first questions people ask is: "How will the park play?" While all sports feature home-field advantages in their stadiums and some have environmental differences (see field goal kicking and altitude), baseball is fairly unusual in that the dimensions of the field aren't consistent beyond the very basic construct of the diamond. With no standardized dimensions for the playing field outside of some very basic rules (commissioner Rob Manfred's office will come down on you like the hammer of Thor if you try to make a right-field fence that's 200 feet away from home), baseball parks can vary quite widely in their dimensions as a result and play much differently from each other -- above and beyond any basic distinctions due to altitude or climate.
So how does SunTrust Park look? On multiple occasions, the team has suggested the park will play similarly to Turner Field but will be a bit better as a hitters' park due to the slightly smaller dimensions in right field. Overall, Turner played as roughly neutral for its history and as a slightly tougher venue for homers than the typical park. To get another, more public guess, I dove into some historical park data and the new park.
What variables go into determining how a park plays? Factor analysis agrees that many of the basic things you might think of: Distance to the fences, height of the fences, altitude and temperature all play a significant role in determining the eventual park factors of a stadium. Foul territory isn't talked about much, but that's also a major player, in that foul outs reduce all other offensive events. Tropicana Field and "The Whatever It's Called This Year" Coliseum in Oakland, both with significantly more foul territory than the pack, are two of the most consistent pitchers' parks in baseball.
While things such as wind speed, humidity and the batters' eye no doubt play a role, wind speed is also erratic, and I found the data too noisy to be of value in projecting general park factors for stadiums. Data such as humidity isn't available on a game-by-game historical basis. And I'm not even sure how to get data for hitting background, short of eye tests at each park when crowds are in the center-field stands (where applicable). But one of the rules of modeling is that you have to go with the data you have.
One very useful source of data I came across was geographic information system estimates of the square footage and foul territory calculated by GIS analyst Scott Bailey.
So, what's different in SunTrust from Turner? The biggest differences in the park dimensions are:
- A shallower right-center power alley
- A right-field corner that is five feet closer to home
- Fences that range from six feet high in left to 16 feet in right, compared to the constant 8-foot-8 fence at Turner
- Less foul territory at SunTrust, indeed one of the smaller foul territories in baseball
- The elevation gets a bump to 975 feet, up from Turner's 942, so it remains the third-highest park in baseball, behind Chase Field in Arizona and Coors Field in Colorado.
In the end, the model worked better than I had hoped. Depending on the factor involved, the physical characteristics mentioned above explained 60 to 80 percent of the park-to-park variance in park factors. What makes this kind of task especially challenging is that the park factors themselves are only rough estimates of an unknowable park factor that we could discover if they played thousands of games a year at stadiums, not just 81.
For the chart below, I have estimated the park factors of SunTrust Park, both overall park factors and those for handedness of batter. To give an example of how to read the chart, the 1.11 factor left-handed home runs indicates that in games played at SunTrust, you would expect 11 percent more home runs in those games than the rest of the parks in the league. (So it's about half the factor for Braves hitters, because they only play half their games at home.)
In the end, despite the higher fence in right, the park characteristics project to make more doubles and triples turn into home runs than the other way around from balls bouncing off the wall. While the 325 feet from home to the right-field corner isn't that far below the league-average distance of 328, the other factors come into play in making SunTrust a projected mild-to-moderate homer-friendly field. The elevation helps the homers, and the small foul territory creates more offensive results that aren't foul outs.
Atlanta is also one of the warmest home cities in baseball, with an average game time temperature from 2014 to 2016 of 80.2 degrees, behind only Arizona (81.1) and Texas at 84.3 (remember, some field have retractable roofs that bring down the overall temperature). And when Texas's new park eventually goes live, SunTrust will be the warmest park without a roof in baseball.
The last question is: Which Braves players will the new park help and hurt the most? While the results aren't going to be extreme -- SunTrust isn't going to be Coors Field or AT&T Park -- lots of games are decided by a single hit at the wrong time. For each player on the 25-man roster and prospect Ozzie Albies, I calculated their OPS (or OPS against for pitchers) in the neutral park I projected versus the projection in this estimated SunTrust Park. A player with an exactly league-average line would expect to gain 10 points of OPS/OPS a season playing in SunTrust instead of a neutral park, so hitters that exceed that become more valuable in SunTrust, and players that fall short become slightly less so (and vice versa for pitchers).
Freddie Freeman is the Braves' left-handed hitter with the most power, and he isn't too shabby at all in the batting average department, so it's not a surprise that he gets the most projected net benefit of any player on the team from the new park. This would make the Brave's long-term contract with Freeman look even more beneficial to the team that it currently is. If these park factors turn out to be correct, the Braves might want to pay closer attention to left-handed power hitters generally and pitchers that can keep the ball down, especially if they're right-handed.