“Football Freakonomics”: Is Momentum a Myth?

The following is a cross-post from NFL.com, where we’ve recently launched a Football Freakonomics Project.

Is momentum a myth? That’s the question we ask in our latest installment of Football Freakonomics. It’s the kind of topic that academic researchers are increasingly interested in – and  the kind of topic that makes a lot of sports fans hate academic researchers.

Why?

Because they take all the fun out of our arguments! Do we really want to haul out a spreadsheet to talk about whether Mike Smith was a bonehead for gambling on 4th down? Or whether icing the kicker is a good idea?

As someone who has one foot in both camps (fandom and academic research), I can see both sides of the argument. In the case of momentum, however, I really want to know the truth – perhaps because it’s the kind of phenomenon that is harder to prove than most.

The best place to start is with a famous (for academia) paper from several years ago, called “The Hot Hand in Basketball: On the Misperception of Random Sequences.” As you can glean from that snazzy subtitle, the authors come down against momentum, arguing that a “hot streak” is really just a random sequence that we misperceive to be more meaningful than it is. 

Ever try flipping a coin 100 times? You’ll be surprised at how many long, unbroken sequences of heads or tails you get. It’s easy to mistake that for a pattern, suggesting some kind of meaning or momentum, but it’s really just a pure illustration of randomness itself. The fact is that if you get 10 heads in a row, the next flip is no more likely to be heads (or tails, for that matter).

And so it is, for the most part, with hot hands and hot streaks and hot quarterbacks. In our Momentum video, you’ll hear Toby Moscowitz, the academic co-author of Scorecasting, discuss how pretty much everyone in football believes in momentum. But, having looked at a lot of NFL data, Moscowitz reaches a sobering conclusion: “There is a much stronger belief in momentum than is warranted by what we see in the data.”

In other words, just because a team has driven down the field three times in rapid fashion to set up a dramatic comeback doesn’t necessarily mean the fourth drive is sprinkled with fairy dust.

Here’s the takeaway: we should be leery of announcers (and coaches and players and fans) talking about “the Big Mo” as if it were a twelfth man who suddenly snuck onto the field and is about to streak, uncovered, into the end zone.

Why, then, do so many of us believe that the Big Mo is a monster?

Consider one example in our video, the Buffalo Bills’ redonkulous 32-point comeback against the Houston Oilers in 1993. As Chris “Mad Dog” Russo puts it: “You’re gonna tell me momentum had nothing to do with that game?!”

Okay, Chris, I’ll take a shot at telling you exactly that. You know why we’re still talking about that game? Because it was a massive anomaly – the kind of comeback that almost never happens. It was so rare that our brains have an easy time recalling it. (We do this with all anomalies – dramatic plane crashes, mass murders, and so on.) And when we recall something so easily, we tend to believe it’s far more common that it actually is.

The truth is that you’re bound to get a wild 32-point-comeback once in a while, just as you’re bound to get a streak of 10 or 12 heads too. But just as the physical world cannot escape gravity, the statistical world cannot escape what’s called “regression to the mean.” Those wild streaks, as fun as they were, have very little bearing on what happens next.  

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  1. James Briggs says:

    Statisticians want everything to be random because that think it would confirm their importance. The problem is they don’t even understand their own argument. The basic meaning of momentum is that knowledge of the past can help us predict the future. If a team scores is it likely there is a reason that they scored? Wouldn’t that reason make them more likely to score in the future? One way to look at it is to ask if there is a reason to believe in the existence of skill. Moving from football to basketball are some people better at scoring in basketball than others. If I claim that a person is skilled at basketball because they make one hundred baskets in a row the denier of skill can say another person missed one hundred baskets in a row. But does that fact that someone missed a one hundred shots in a row support or negate my claim. A statistician could say if he flips enough coins some will come up heads one hundred times and in a row and some will come up tails one hundred times in a row. The problem is the statistician is seduced by the coins. He thinks if he twists events to look like coins then they are coins. Tim Tebow’s quarter back rating goes from 85 in the first quarter to 107 in the last quarter are we to believe that is pure luck? Tom Brady, converted 21 of 33 4th quarter comeback opportunities (64%) while Tom Rattly converted 1 of 11 opportunities for (9%). I would gladly bet that Tom Brady will make a 4th quarter comeback before a quarterback picked at random by a statistician.

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  2. James Briggs says:

    extinction

    In the operant conditioning paradigm, extinction refers to the decline of an operant response when it is no longer reinforced in the presence of its discriminative stimulus. Extinction is observed after withholding of reinforcement for a previously reinforced behavior which decreases the future probability of that behavior.

    If the players are not rewarded for making shots wouldn’t extinction take place. Why not take streak player and reward them for making consecutive shots. See if that has any effect.

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  3. MAL says:

    I would argue that momentum in football is very real and even quantifiable. Football game is not a series of unrelated events. Each play influences the next one. A string of positive plays increases a probability of the next play being positive due to a few factors:
    1. It alters the game plan of the other team. Coaches come into games with a plan. They know which play to call in which situation and what players to put on the field. When things don’t go as planned, they’re forced to alter it. Let’s say for example a quarterback gets sacked and hit a couple of times because a left tackle gets continuously beat by a linebacker. This forces the coach to pull out otherwise eligible receivers into blocking thus limiting the amount of offensive plays that can be called, which reduces a probability of a successful offensive play.
    2. The crowd! The crowd in football plays a significant role in the outcome of the game. The crowd becomes louder if the home team continues making positive plays and it withdraws from the game if the away team gets on the roll. If you watch a football game you’ll notice that the crowd gets louder when the home team is on defense and quieter when the home team is on offense. The reason for that is because the outcome of any offensive play often largely depends on the pre-snap adjustments which are made verbally. By making noise when the away team is lining up to snap the ball, the crowd impairs team’s ability to communicate which causes more mistakes such as false start penalties, missed blocking assignments, incorrect routes ran by the receivers
    3. The human factor. Athletes confidence, just like any other human being, depends on the amount of success. A wide receiver who just dropped a pass, may over-think the next catch going his way, whereas a guy who just made a spectacular catch will trust his instincts.

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  4. James Briggs says:

    Tebow, Broncos do it again, beat Vikings 35-32 – 11 minutes ago
    Tim Tebow led yet another late rally, passing for a season-best 202 yards and two third-quarter touchdowns to help the Denver Broncos win their fifth straight game with a 35-32 victory over the Minnes…

    There it is. We had a prediction and it came true. I think they are right about basketball shots but football is different. Its time for the anti-momentum people to put up or shut up.

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  5. Nick Hodges says:

    A coin flip and a football game are drastically, radically different things. A coin flip is a random event, presumably not affected by human emotion or activity.

    A football game? Not so much.

    The fact that statistics (allegedly) disprove the notion of momentum in a football game doesn’t mean it doesn’t exist. It means that statistics can’t prove it’s existence. I’d wager that a number approaching 100% of professional players and coaches will tell you that it exists, and that they can feel it. Therefore, it exists. QED.

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