MLB All-Star - Lesson 04 - Ballpark Factors

Jonathan Bales is the author of Fantasy Baseball for Smart People—a 197-page book created to help you win playing daily fantasy baseball on DraftKings. As a daily fantasy baseball player, you’re searching for every possible edge you can gain on the field. One of the potential…

By DK Playbook May 31, 2020, 9:00pm PDT

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Jonathan Bales is the author of Fantasy Baseball for Smart People—a 197-page book created to help you win playing daily fantasy baseball on DraftKings.

As a daily fantasy baseball player, you’re searching for every possible edge you can gain on the field. One of the potential advantages that’s most commonly overlooked by novice players is using a ballpark’s hitter-friendliness to project players.

For a variety of reasons, certain MLB ballparks are easier to hit in than others. Everyone knows of the most extreme of these: Coors Field. Due to the thin air in Colorado, the ball carries out of Coors Field like no other ballpark in baseball.

Most users know that players in games at Coors Field should get a bump, but the same logic should be applied to all games, even if in a smaller capacity. Park factors can have a massive impact on player performance, so it would be unwise to overlook the stadium in which a game is being played.

Quantifying Park Factors

One of the difficult aspects of determining a park’s hitter-friendliness is separating the offense from the stadium. A team with an amazing offense or really poor pitchers could make a ballpark look more hitter-friendly than what’s actually the case.

To get a real sense of a park’s hitter-friendliness, we need to remove the team from the park in some way. To do that, I examined each team’s total bases over the past four seasons, broken down by home versus away. I used total bases because they’re a good proxy for DraftKings production; total bases represent fantasy scoring.

Below, I charted the percentage of each team’s total bases that occurred at home. The idea is that the teams with the most production at home are those that benefit the most from hitter-friendly parks. Since we’re adjusting for offensive quality (by examining road stats), we can get a better sense of which stadiums are the friendliest to batters.

Yowzers. Only one team in baseball has seen more than 52 percent of their total bases come at home since 2011. It’s the Rockies at over 57 percent. That’s insane.

So yeah, we kind of knew that Colorado would have the best park, but there’s still a pretty large difference between a park like Fenway and Kauffman Stadium in Kansas City (around a 10 percent drop in total bases).

Handedness

Another way to break down park factors is by handedness. Certain parks are obviously more hitter-friendly to lefties than righties, and vice versa. The Red Sox have an extremely favorable ballpark for right-handed hitters, for example, but one that’s overrated for lefties.

FanGraphs has a nice breakdown of park factors by handedness. One thing to keep in mind is that park factors can “change” if you analyze a small amount of data. As long as a stadium’s dimensions weren’t recently changed, I like to analyze as large of a sample of data as possible.

I also sometimes prefer to analyze ballpark factors as a whole, except in the case of extreme parks like Fenway that have some sort of weird architecture (The Green Monster). If you want to use handedness, you’ll also need to consider how often a particular player hits the ball to certain parts of the field, which can become a lot of work.

Weather and Park Factors

One of the most overlooked aspects of ballpark factors, in my opinion, is that much of “hitter-friendliness” in a particular city is due to weather patterns. Weather plays an absolutely crucial role in fantasy baseball production; things like temperature, air pressure, humidity, and wind can really alter how a baseball travels.

Coors Field is the perfect example of this (and again the most extreme). The ballpark itself is humongous, but the favorable air density for hitters more than makes up for it. We see similar effects in Globe Life Park in Arlington and Chase Field in Arizona—two parks that are very hitter-friendly, likely due mostly to high temperatures throughout the year. This is another reason to potentially favor overall ballpark factors over those broken down by handedness; a lot of the benefits provided by a park could be due mostly to things like weather that affect all hitters equally.

It’s important to know these things because it can help to understand when a park might not be as hitter-friendly in a given game as the overall numbers suggest. A park like Globe Life might be much more hitter-friendly than Yankee Stadium in April, but not in August, for example.

Getting Value Based on the Park

When the Rockies are at home, the prices of their players (and opponents) increases on DraftKings. There’s no doubt about that. Whether or not they increase enough is tough to tell.

However, I think ballpark factors are a very important variable that, for the most part, aren’t priced into players’ salaries across the board. You can often find value on guys who are playing in hitter-friendly parks that aren’t as obvious as Coors.

The other thing to consider is that park factors aren’t widely used by the general daily fantasy baseball playing community, which means you can potentially use them to find an edge in tournaments. Outside of Colorado, I don’t think you’ll see ballparks alone dramatically increase usage in tournaments. If you can get access to a high-upside offense in an underrated hitter-friendly park, like Chase Field, and still see moderate to low player usage, that’s a huge victory in GPPs.