The Z Files: 2026 Pitching and Hitting Park Factors

Back in the day, I used to write an annual piece called "Park Factors: A Necessary Evil." The premise was that park factors aren't perfect, but it's better to include them in analysis than to ignore them.

It's been a while since I updated the piece. At the time, DFS and prop betting weren't nearly as popular as they are now. The topic could use a refresh, so let's do it.

The concept of park factors is a measure of how a venue plays, removing all bias, especially the quality of the home team's hitting and pitching. They are calculated as indices where 100 represents neutral. Levels over 100 indicate that the metric is enhanced by the park, while numbers under 100 denote venues that suppress it.

The strength of the team's offense and pitching is accounted for by comparing the team in question's numbers and their opponents at home to those on the road. Using home runs as an example:

HR Park Factor = ((Team HR at Home + Opponent HR at Home) ÷ (Team AB at Home + Opponent AB at Home)) / ((Team HR Away + Opponent HR Away) ÷ (Team AB Away + Opponent AB Away)).

This formula yields neutral as 1.00. Depending on the application, factors can be left in this form, or they can be multiplied by 100.

Comparing performance home and away is designed to flesh out the quality of hitting or pitching. A powerful lineup will consistently clear the fence at home and away. A strong pitching staff will limit long balls at home and on the road.

The premise is solid but not perfect. As an extreme, let's say the Boston Red Sox have nine Johnny Peskys, that is, hitters with a proclivity for clanging balls off the right field foul pole in Fenway Park. The same type of contact on the road would hook foul, with the at-bat probably not ending in a home run. The HR factor for Fenway Park would be well over 100 because the lineup takes advantage of a quirk in the venue. A typical team may have a player or two specializing in fly balls down the line, so the example is clearly hyperbolic, but it shows that hitting or pitching bias may not be completely washed from the calculation.

The rest of the bias is eliminated by using a rolling three-year average. That is, the 2026 park factor averages the factors from 2023-2025, assuming the venue remained the same over that stretch. For example, "Walltimore" in Camden Yards reset the three-year rolling average. There are only two seasons with the renovation, so the 2026 factors in Baltimore only consider 2024-2025.

Fortunately, the Tampa Bay Rays moved back into Tropicana Field after spending last season at George Steinbrenner Field. While the dimensions are the same, there is new turf, and the lighting is better, so the park may play a bit differently. Even so, relying on the factors from 2022-2024 makes sense.

Unfortunately, the Athletics returned to Sutter Health Park, so we're stuck with one year's worth of data. Some cite the numbers from its usage as the home park of the Sacramento River Cats, Triple-A affiliate of the San Francisco Giants. The problem is park factors compare how the venue plays relative to other places, and the River Cats are in the Pacific Coast League, perhaps the minors' most hitter-friendly league. Compared to other venues in the PCL, Sutter Health favors pitchers, but it boosted hitting in the majors. The dimensions of most minor-league parks are comparable to major-league yards. The primary difference is that minor-league parks are subject to more open-air effects since they only have one deck of seats. Major-league parks have multiple decks, which lessen the impact of the wind. This can hurt or help, depending on the direction of the breeze. For most of the season, Sutter Health Park experiences the "Delta Breeze," which usually blows out towards right field. With only one season of data, we're stuck with 2025 to generate Sutter Health Park indices.

What follows are the 2026 Park Factors for the 30 major-league venues, color-coded by the extent of their influence. Over 100 means the venue enhances the metric, while under 100 indicates that it suppresses it. The color code is relative to the pitcher/hitter. For example, a home run factor of 115 is terrible for pitchers but great for hitters.

Next time, I'll detail how park factors are applied to preseason projections and in-season analysis, which will include setting lineups, DFS, and prop betting. In addition, venues with seemingly contradictory factors will be grouped together and discussed.

Key:

• Great
• Good
• Neutral
• Bad
• Terrible

Pitching Park Factors

Right-Handed Batter Park Factors

Left-Handed Batter Park Factors

Switch-Hitter Park Factors