Select Home Run Park Factors, Visualized

If you read my Daily Grind column, you should be familiar with what I call the Factor Grid. It’s a simplification of the freely available information over at FanGraphs Guts! There is an obvious reason we should care about park factors – they affect a player’s performance. In particular, the home run park factors can really benefit fantasy owners. After all, a home run helps in four categories. After games played, it might be the best predictor of fantasy success. Let’s take a look at some relevant factors.

The “Basic” column refers to overall run scoring. A park factor of 100 is considered league average or neutral. The 126 HR factor in Denver means hitters bash 26 percent more home runs at Coors Field than a neutral stadium. Similarly, home run production is reduced 22 percent in San Francisco. I’m told the “marine layer” is to blame.

Numbers are numbers, but thanks to ESPN’s park overlay tool, we can visualize why certain parks perform as they do. Detroit’s Comerica Park is possibly the most neutral in baseball (Nationals Park is similarly neutral), so we’ll use the Tigers’ home base as our overlay park.

Yankee Stadium

Yankee Stadium

No power hitter complains when he visits Yankee Stadium, but lefties really benefit from the short porch. How short is the porch? Well take a look. The corner isn’t outlandish compared to Detroit, but the gap is definitely a lot closer to home plate.

Coors Field

Coors Field

The friendliest park in baseball is pretty huge. Detroit’s park only exceeds its dimensions from center to right-center. Remember back when Colorado wasn’t storing their baseballs in a humidor?

Progressive Field

Progressive Field

The homeland of the Cleveland Indians has a reputation as being extremely stingy to right-handed bats while allowing more than its share of long balls to lefties. The overlay surprises me. I can see why lefties would enjoy the friendly right-center gap, but doesn’t it look like righties are scarcely disadvantaged? The answer is actually quite simple, left field has a 19 foot fence compared to a nine foot fence in right field.

AT&T Park

AT&T Field

What looks like a short porch in right field is offset by a very large wall. It was no impediment to Barry Bonds, but most other hitters probably curse its existence. The so-called marine layer does the rest of the work.

Nationals Park

Nationals Park

Here’s our other “neutral” park. As you can see, using a neutral park as the overlay can be a bit misleading. Nationals Park has some funky dimensions. It’s deeper in the corners and shallower in the gaps than Comerica. The wall is fairly normal, but it’s 12 feet high from right field to center.

Fenway Park


Fenway is a fun place to conclude today’s exercise. Everybody knows about the Green Monster which helps its share of right-handed hitters. The wall prevents left field from playing like a bandbox, although righties do hit 12 percent more doubles than a neutral stadium (tied first with Coors Field). If lefties don’t hit the ball right on Pesky’s Pole, they’ll find the wall gets deep fast. Most casual baseball fans don’t realize lefties lose about 16 percent of their home run hitting capacity in Boston.

Parting Thoughts

If you’d like to continue the analysis on your own, visit ESPN’s park overlay tool. I also recommend Seamheads for wall heights and other data.

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Brad is a former collegiate player who writes for FanGraphs, MLB Trade Rumors, The Hardball Times, RotoWorld, and The Fake Baseball. He's also the lead MLB editor for RotoBaller. Follow him on Twitter @BaseballATeam or email him here.

7 Responses to “Select Home Run Park Factors, Visualized”

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  1. Cicero says:

    And yet the Rockies are 5th in HR/9 allowed at home

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  2. Compton says:

    To what extent do environmental factors affect the overall park factor? E.g. The altitude of Denver, the marine-layer effect on the west coast, or the jet stream at New Yankees Stadium(not sure about that one).

    I can remember seeing all of Cano’s 2013 home runs overlayed on Safeco Field, and most if not all still would have been home runs. I’m wondering if that’s necessarily true. Would a ball hit at Yankee Stadium travel the same distance as one hit at Safeco?

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    • Brad Johnson says:

      Atmospheric conditions definitely affect how far a ball will travel. I’m not sure we have a good way to measure it. In my daily column, I note the day’s atmospheric conditions on a 0-10 point scale, but I’m still unsure how best to incorporate the information. I know if the weather is a 10/10 in Colorado, I really want hitters in that game. But how should I view a 10/10 in Detroit? Or AT&T. I don’t have the necessary data to test.

      The Jet Stream is a little tongue in cheek joke. The actually jet stream is way way up there. Sometimes the ball seems to fly when it reaches a certain height, which is probably a result of the park/prevailing wind conditions.

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  3. Satoshi Nakamoto says:

    When are the guys from that MythBusters TV show going to look into this?

    Compare flyballs hit in dry conditions versus very humid conditions?

    Like comparing the Diamondback’s ballpark to San Francisco where there’s lots of moisture in the air?

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  4. Rob The "Dream Machine" says:

    Great Article! Thanks for the info!

    Re: “Most casual baseball fans don’t realize lefties lose about 16 percent of their home run hitting capacity in Boston”…

    And by ‘Most casual baseball fans,’ you mean, all baseball fans in the world who have not read this article or don’t work for fangraphs or the red sox organization. I mean, that’s deep info man!

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