An Introduction to Park Factors and Schedule Factors

Last week I wrote an article on Weekly Park Factors. Apparently, that article was a source of some confusion. Weekly Park Factors are merely a look at the hitting and pitching environments (The combined Park Factors for the stadiums they are playing in that week). While that’s a relatively easy concept to understand, I never explained to you how I created my Park Factors and why. So, let’s do that now.

The Park Factors

On February 27th, 2010 Steve Slowinski wrote an article on Fangraphs titled “Park Factors”. Here’s an excerpt from that article: 

“The Noble Goal”

If you had the power to do so, you’d want to know how every single plate appearance would play out in all 30 MLB parks. If it turned into a single in the park of interest and then went for a single in 25 other parks, an out in three, and a double in one, you’d have a good sense of the way the parks played. The park that allowed the double would be a hitter’s park and the ones that created outs would be more pitcher friendly. But unfortunately, we don’t have that kind of data.

We want to know how parks influence each moment of the game, but we simply don’t have granular enough data to really get there. A ball hit at 15 degrees directly over the shortstop while traveling at 93 miles per hour will travel how far and land where? That’s basically what we want to know for every possible angle and velocity, but we just don’t have the data and we don’t have it for every type of weather in every park.

Instead, we have to settle for approximations.”

Now, we do have that data. No more approximations.

The Importance of Handedness and Hit Location

Intuitively, we all know that, because of field dimensions, if the same batter hit Left-Handed at Yankee Stadium for 81 games, he’s likely to hit more homeruns than if he were to play his 81 home games at Oracle Park in San Francisco. Additionally, it doesn’t take a savant to realize that a 370 ft. fly ball down the Left Field line will be a homerun 100% of the time while a 370 ft. fly ball to Center Field will never result in a homerun. Handedness and hit location matter. The StatCast data available on Baseball Savant allows us to see details such as how hard a ball was hit (Exit Velocity), trajectory (Launch Angle), whether it was hit by a Right-Handed Batter or a Left-Handed Batter, the distance a ball was hit, and by using the X and Y coordinates, where the ball was hit. Using all of this available data I determined if the ball was Pulled, Pulled-Alley, Centered, Oppo-Alley, or hit Oppo to see these impacts on the flight of the ball 2022 and 2023.  Why 2022 and 2023? These were the first two seasons where MLB used a humidor in all 30 ball parks.

All Batted Ball Events with an Exit Velocity between 90-110 MPH and a Launch Angle of between 15 and 35 degrees in 2022 and 2023

As you can see from the chart above, a pulled ball at an Exit Velocity (EV) between 90 and 110 MPH and a Launch Angle (LA) of between 25 and 35 degrees will fly 35.4 ft. to 46.6 ft. farther than a ball at those same LA’s and EV’s when they are hit to the opposite field. Those travel distance differences are akin to the difference between hitting at Coors Field and hitting at sea level. In short, whether a ball is pulled, centered, or hit the opposite way matters tremendously yet it is missing from all of the expected stat analysis that I’ve come across to date (apologies to any work that I haven’t seen). To read more about the forces that impact the flight of a batted ball I suggest checking out this article here .

Park Factors Primer

Let’s remember what Steve Slowinski wrote back in 2010, “If you had the power to do so, you’d want to know how every single plate appearance would play out in all 30 MLB parks.” Now that we do have that power, I set out to find the results of all Batted Ball Events (BBE) from 2022 and 2023 by EV, LA, handedness, hit location and whether the ball was pulled, hit to the opposite field, pulled to an alley, hit to the opposite alley, or centered. Taking all of these factors into account, we come up with a baseline for how all of the BBEs played out in all 30 MLB stadiums. Below are some samples of these baselines.

All BBEs at an EV of 98 MPH and a LA of 26 degrees in 2022-2023. 

All BBEs at an EV of 98 MPH and a LA of 26 degrees that were Pulled 2022-2023. 

All BBEs at an EV of 98 MPH and a LA of 26 degrees that were hit to the Opposite Field 2022-2023. 

All BBEs at an EV of 98 MPH and a LA of 26 degrees that were hit to Center Field in 2022-2023.

When we analyze these sets of data, we can further see why it’s so important to use more than just EV and LA. If we only use those two factors, we would be assigning an expected AVG of .392 and an expected HR rate of 16.5% for every ball hit at an EV of 98 MPH and a LA of 26 degrees. However, if that ball that’s hit at 98/26 goes to Center Field it’s an out 89.3% of the time with a 0% chance of leaving the yard. However, when Pulled, that same 98/26 batted ball has a 85.2% of being a hit with a 63% chance of being a home run. This is yet another illustration of why Pulled, Centered, or Oppo matter.

Once I assemble all of the outcomes for the season, I can then generate the expected stats for each BBE. This data now gives me the Average MLB Stadium to compare the Actual Outcomes in individual stadiums to the Expected Outcomes in the Average MLB Stadium. If the Actual Outcomes equal the Expected Outcomes, then their Park Factor is 100. So, for example, if a ballpark yields 58 home runs to Right Field on 600 BBE’s, and the expected home run total in the Average MLB Ball Park’s Right Field is 58 on those same 600 BBE’s, then the Right Field Park Factor is 100. If a ballpark yields 58 home runs and the expected home run total in the Average MLB ballpark is 50, then their right field Park Factor is 116 (58 Actual HR’s divided by 50 Expected HR’s). Below is a sample of how these factors look for the Right-Handed Batter’s BBEs to Left Field for Oriole Park at Camden Yards for 2022 and 2023.

Actual Stats by Right-Handed Batters at Camden Yards in 2022 and 2023

Expected Stats by Right-Handed Batters at the Average MLB Park in 2022 and 2023

Park Factors for the 2022 and 2023 Seasons

Here are the basic Park Factors for each MLB Ball Park as it relates to Pitchers, Right-Handed Batters, and Left-Handed Batters:

Park Factors for the 2022 and 2023 Seasons by Sections of the Ball Parks

How Do Schedule Factors Differ from Park Factors?

Park Factors are an evaluation of how each stadium performed over the last two seasons where the Schedule Factors are a weighted measure of all of the stadium’s Park Factors that each team will play in for 2024. For example: The Right-Handed Batter HR Factor to Left Field at Camden is 51. However, the Right-Handed Batter HR Factor to Left Field for the Orioles entire schedule in 2024 is 79, and for Week 3, where they play 3 games at BOS and 3 at home, the HR Factor is 97. Remember, the baseball season may be 162 games long, but our fantasy baseball season is 27 unique weeks where we need to maximize our line-ups. Hopefully the Weekly Schedule Factors will be another tool in your box to give you an edge.