UPDATE August 15: Hey, so the internet is vast, and things often get overlooked. Turns out our buddy Scott Kacsmar (@CaptainComeback) already did the update you see below back in April, albeit only looking at win-loss records. He also summarizes straight-up results for the other non-Sunday-afternoon games. I'm a stickler for giving proper credit to previous work, so check out his piece if you're interested. As far as I know, though, this XP is the only place with an update of winning percentages against the spread.
Calling all gambling degenerates! Sleep science says that, when a west coast (i.e., Pacific time zone) team plays an east coast (i.e., Eastern time zone) team on Monday Night Football, the former benefits from humanity's late-afternoon energy boost while the latter is searching for a soft place to lay their heads (no tuck, please). Therefore, you should pick the west coast teams. And it turns out -- this being science and all -- west coast teams do in fact win straight up 63.5% of the time by an average of 14.1 points, and beat the Vegas spread 67.9% of the time. Well, at least that's what sleep science said in 1997 during a conversation about the NFL circa 1970-1994. Sounds like we need an update.
Even though the pre-2000 internet was mostly Lycos, I was able to cobble together MNF betting lines from various sites going all the way back to 1995. Here are the 21 east-west MNF matchups since then (winners against the spread in bold):
09/25/95 -- San Francisco (-10.5) @ Detroit. Final score: Lions 27, 49ers 24.
11/20/95 -- Miami (-1.5) vs. San Francisco. Final score: 49ers 44, Dolphins 20.
11/11/96 -- San Diego (-4) vs. Detroit. Final score: Chargers 27, Lions 21.
12/02/96 -- San Francisco (-10.5) @ Atlanta. Final score: 49ers 34, Falcons 10.
12/23/96 -- San Francisco (-9.5) vs. Detroit. Final score: 49ers 24, Lions 14.
09/29/97 -- San Francisco (-3.5) @ Carolina. Final score: 49ers 34, Panthers 21.
11/10/97 -- San Francisco (-4) @ Philadelphia. Final score: 49ers 24, Eagles 12.
09/14/98 -- San Francisco (-6) @ Washington. Final score: 49ers 45, Redskins 10.
11/30/98 -- San Francisco (-13) vs. New York. Final score: 49ers 31, Giants 7.
12/14/98 -- San Francisco (-10) vs. Detroit. Final score: 49ers 35, Lions 13.
01/03/00 -- Atlanta (-6.5) vs. San Francisco. Final score: Falcons 35, 49ers 29.
10/01/01 -- New York (-3) vs. San Francisco. Final score: 49ers 19, Jets 17.
11/25/02 -- San Francisco (-7) vs. Philadelphia. Final score: Eagles 38, 49ers 17.
12/02/02 -- Oakland (-7) vs. New York. Final score: Raiders 26, Jets 20.
10/27/03 -- Miami (-3.5) @ San Diego. Final score: Dolphins 26, Chargers 10.
11/17/03 -- San Francisco (-4) vs. Pittsburgh. Final score: 49ers 30, Steelers 14.
10/10/05 -- San Diego (-3) vs. Pittsburgh. Final score: Steelers 24, Chargers 22.
12/05/05 -- Seattle (-4) @ Philadelphia. Final score: Seahawks 42, Eagles 0.
09/22/08 -- San Diego (-8) vs. New York. Final score: Chargers 48, Jets 29.
12/05/11 -- San Diego (-3) @ Jacksonville. Final score: Chargers 38, Jaguars 14.
12/19/11 -- San Francisco (-1) vs. Pittsburgh. Final score: 49ers 20, Steelers 3.
Clearly, the MNF trend continues to this day: West coast teams over the past 17 years had a 16-5 record against east coast teams, with an average victory of 18.5 points (32.6-14.1) and a 76.2% winning percentage against the spread. They're currently on a four-game winning streak of the 37.0-11.5 variety.
Of course, we've got a few complications. First, my god, I had forgotten how much of a juggernaut San Francisco used to be on Monday nights. From December of 1996 through the end of 2001, they single-handedly carried the torch for west coast teams, covering nine straight against the spread. And in the last four years of their dynasty (1995-1998), San Francisco was football's equivalent of Death Row Records, piling up eight victims by an average margin of 20.5 points (33.9-13.4).
So, in the interest of fairness, let's set Shug Seifert, Mooch Dogg, and company aside for a moment. How have west coast teams fared since San Francisco dominated the east-coast-west-coast rivalry? In the subsequent 14 years, they've posted a 63.6% winning percentage against the spread. Still well into the black in terms of profit.
The other complications are what the study's authors controlled for in their analysis: relative team strength and game venue. I know this isn't technically ideal, but we'll use the line as a measure of the former and not bother with control groups. (I only have so much free time on my hands.) Here's how the 21 results look when split out according to those two factors:
West coast home favorites: 7-3
West coast road favorites: 6-1
East coast home favorites: 0-3
East coast road favorites: 1-0
Over the past 17 seasons, west coast favorites have been equally successful at home and on the road, and they've covered the spread more often than east coasters of similar quality (13-4 vs. 1-3). Granted, these are small groups with a heavy Death Row influence (like D12), but I don't think we can ignore the results when they conform so nicely to a previous test on an independent sample.
Whether this is really a sleep effect or some other variable explains the trend is another matter entirely. Correlation? Sure seems like it. Causation? That's for the academics to figure out. For instance, back when I dated the cousin of a former NFL offensive coordinator who shall remain nameless, said assistant regaled me with stories of caffeine binges in the locker room before games. A pot of coffee per player has to be a huge middle finger to circadian rhythms, right? (Although, admittedly, his team's results might not lend much credence to my anecdotal theory.)
Now, for the bad news, which some of you probably realized already. Although it's just a simple byproduct of geography and the whims of NFL scheduling gods, there have been only 21 qualifying matchups in the past 17 years. And if you include the study's sample of MNF games from 1970 to 1994, it's 84 qualifiers in 42 years. In other words, as much of a cash cow as this trend appears to be, NFL bettors can only take advantage of it about twice per season. To boot, you'll have to wait until (at least) 2013 because no games qualify in 2012. It's standard to judge betting systems on a long-term basis, but this is one requires a geological time scale.
With the proliferation of night games (read: advertising money grabs) over the past two decades, perhaps the MNF trend extends to other days of the week. If so, it would make for a much more useful system. Given the potential profit margin, exploring this idea sounds like a worthy mission should you choose to accept it.
Here's a link to the actual study cited in the Deadspin article: