The 2018 schedule for the Seattle Seahawks was released yesterday, and now we know where and when the Hawks will be playing this upcoming season. Many fans immediately smiled when seeing the Week 1 matchup for Seattle will be against the Denver Broncos, as Denver is just 14-18 over the last two seasons, including a 5-11 finish in 2017.
However, this fails to take into consideration not just the home field advantage that the Broncos have at home, it fails to pay notice to the fact that in spite of being under .500 over the last two seasons, they are undefeated at home early in the season. When rumors that the Seahawks would open the season in Denver emerged, Mookie included a tweet that I sent out regarding Denver’s home field advantage in September, but for those who missed it, here it is.
This would suck.— John Gilbert (@SeahawksMachine) April 19, 2018
Broncos home field advantage is better earlier in the season, due to higher temperatures I would guess.
Broncos have won 79% of their September home games since 1978. https://t.co/Z1fjLYcB8S
Obviously fans were quick to point out that this included all of the years when the Broncos had John Elway and Peyton Manning at quarterback, while in 2018 they are likely to have Case Keenum under center. However, the Broncos early season home performance numbers hold steady regardless of who is at quarterback. For a few more stats about the difficulty of the matchup the Hawks face to open the season, here are a few more tweets on the subject.
Broncos are 14-18 over the last two seasons.— John Gilbert (@SeahawksMachine) April 19, 2018
And 5-0 in home games played on or before October 1.
Denver wins only 62% of their home games when the temperature is 45 or less, but wins 78% of games when it's 70 degrees or warmer.— John Gilbert (@SeahawksMachine) April 19, 2018
Now, some readers may think that the outcome of a football game is unlikely to be highly impacted by the temperature at kickoff, so I present to you the following chart which looks at the Broncos home winning percentage in relation to the temperature at kickoff.
To get an idea of the average temperature in Denver during September, here is a chart from weatherspark.com of the average high and low temperatures for the month, with confidence banding included.
In short, ninety percent of the time the high temperature in Denver on September 9th is between about 71 and 90. Referring back to the historical data on the Broncos record by temperature, Denver is 43-12 (.782) over the last four decades when the temperature at kickoff is above 70.
Obviously this doesn’t mean that Seattle is certain to lose its opener, but it does make it readily apparent that it will be a very difficult matchup for the team. They will need to be ready to play in order to battle the thin air of playing at altitude, as well as playing on a grass surface. When playing on grass the last two seasons the Seahawks are just 4-6-1, and only 6-8-1 over the last three years.
Now, I’m not a medical professional - though I did stay at a Holiday Inn Express on Sunday night - so if any of our commenters who work in the medical profession have a better explanation than the relationship between hemoglobin release and temperature, please chime in in the comments. For a long time I assumed that it was the fact that air is more dense at cooler temperatures, which I figured would provide more oxygen to the players at cooler temperatures. However, I have been informed by someone with better more knowledge on the subject that the hemoglobin item would be far more likely to be the cause.
That said, I haven’t seen any definitive research on what exactly is the difference between the body’s consumption and usage of oxygen at different temperatures, so if you have knowledge on that matter, please share it with us as we’ve still got four and a half months to fill between now and the start of the season.