It’s 2014, Sunday morning week 14: game day. It’s time to make the final changes to your fantasy football lineup, and you need a win — badly. You have one last RB slot to fill, and you’ve narrowed your choices down to two split-time guys:
Steven Jackson – The veteran Falcons running back has put up some numbers lately; he’s averaged just under 10 fantasy points in his last 4 games. This week he’s got a matchup against a below average Green Bay rush defense. So why not play him? Well, for one thing the game will be played at Lambeau Field, where the game time temperature is forecast to be 32*F — something to which a lifelong dome ball-carrier may not be accustomed.
Jeremy Hill – Cincinnati’s newest starting rusher has come on in a big way since Giovani Bernard went down with an injury. Hill has averaged 12.8 fantasy points in his last 5 games, and like Jackson, he has a matchup against a sub-par Pittsburgh Steelers rush defense. The Bengals are at home, and though it’s going to be cold (41*F), it’s downright balmy compared to Green Bay.
Both opposing run defenses are equally crappy1, but the Bengals are at home in slightly warmer weather, so you go with Hill. Plus, old men don’t perform well in cold weather, just ask William Henry Harrison. But is your instinct right? Is weather or home/away status really related to running back performance?
Sunshine on a Cloudy Day
To examine the effect of home/away status on running back fantasy points, we looked at every game a running back has played from 2000 to 20142. We then compared running backs at home (8,227 cases) vs. running backs on the road (8,195 cases) to see if there was a difference in their fantasy performance. During home games, running backs generally did score more points, but only to the tune of 0.7 fantasy points per game3. That’s hardly enough to make you think twice before starting a running back only because he’s playing on the road.
But what about weather? As the temperature and other weather conditions change, do running backs’ fantasy points also change? Using the same set of data, we correlated game time temperature, humidity, and wind speed with running back fantasy points4. Again we came away empty handed: weather and running back fantasy points were not related.
The Interaction Effect
So neither temperature nor home/away status have a considerable influence on running back performance. But there has to be something behind the lore of playing in Lambeau or Soldier Field in frigid temps, right? Another possibility is that weather and home/away status could “mix together” in some interactive way to influence running backs’ fantasy performance.
Using this idea, we looked at the relationship between the combination of playing at home or on the road AND playing in the cold weather with running back fantasy points scored. Ultimately, no combination of home or away status and game time temperature meaningfully affected running back fantasy points5.
Under the Dome
What if we limit the analysis to teams who play their home games in domes? Shouldn’t plummeting temperatures hit teams who play half of their games indoors the hardest? Maybe. An article from Advanced Football Analytics revealed that compared to teams who play their home games outdoors, dome teams have a markedly worse winning percentage when playing in cold weather — especially when the temperature drops below 40*F6.
Given these findings, we wanted to see if dome teams’ running backs experience a similar decrease in points when playing outside in the cold. To do this, we compared the relationship between temperature and fantasy points for dome running backs and non-dome running backs. As can be seen in the scatterplot below, there really isn’t much of a relationship between temperature and running back fantasy points, regardless of whether non-dome or dome running backs are playing in the cold. In fact, the correlation for each group is almost identical — and they are both nearly zero.
Taken together, these different analyses suggest that despite common wisdom, home/away, cold/warm, and dome/non-dome distinctions don’t make much of a meaningful difference in RB fantasy performance.
The takeaway is clear: while we are all looking at every aspect of the game to get the upper hand in fantasy football, sometimes we simply overthink things. The decision you made week in 14 of 2014 is a prime illustration. Steven Jackson stiff-armed Old Man Winter to rumble for 13 fantasy points, while Jeremy Hill was held to only 6 fantasy points at home in a warmer environment.
1 The Packers and Steelers rush defenses both end the year in the bottom third of the league.↩
2 2% of cases had missing data for temperature, dome temperatures were excluded↩
3 p<.05↩
4 We did not use precipitation data↩
5 r = .035**, r2 = .001↩
6 Dome Teams: ATL, DET, IND, MIN, NO, and STL (and DAL after 2009 and ARI after 2005)↩
7 Credit for the photo: http://nextimpulsesports.com/2013/12/09/30-best-photos-incredible-eagleslions-snow-game/7/↩