Buzzer Beater: The Science Behind Comebacks

We all love a good comeback story. Who doesn't remember Super Bowl LI, in which Tom Brady's Patriots mounted the biggest comeback in Super Bowl history. Midway through the third quarter, the New England Patriots were trailing the Atlanta Falcons by a colossal 25 points (28-3). However, Brady's offence managed to score 31 consecutive points in the remainder of the game, while the Patriot's defence did not allow any more scores by the Falcons, handing the first Super Bowl to be won in overtime to the Patriots. Another great comeback story is the 2005 Champions League final between Liverpool FC and AC Milan. After only one minute, the English side was already trailing and by half time the Italians had increased their lead to a convincing 3-0. In the second half however, Liverpool managed to score three goals in only six minutes to tie the score and ultimately win the game in the following penalty shoot-out.

However, when you look past the excitement of witnessing a comeback, it actually is a really weird thing to happen. How is it possible that a team, that was so much weaker than their opponents is suddenly much stronger than that same opponent in the same game? Logically speaking, that doesn't make any sense. Maybe comebacks are just pure luck or maybe whether it happens or not is completely random, but this doesn't feel right either. We have all seen games where you just knew that a comeback was coming even before the team managed to complete it. A different way of looking at a comeback is to describe it as an extensive period of positive momentum towards the end of a game which results in a win. Described in this way, a comeback is just a unique type of momentum that happens at a certain time and with a certain outcome and to understand why and when comebacks can happen, we simply have to look at the science of momentum.


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What is momentum and how does it work? First of all, research on this concept defines momentum as: "a force that dictates the ebb and flow of a competitive event" (Higham, Harwood, & Cale, 2005). In other words, each game, match or competition has a natural flow of performance, sometimes one athlete or team is doing better, and sometimes the opponent is doing better. It is interesting to note that in the pure definition of momentum, there is no mention of athletes or teams being able to influence this momentum. It is merely described as a force.

If we take a closer look at the concept of momentum it can be divided into two different types (psychological and behavioural) and two different directions (positive and negative). Psychological momentum is defined as “an added or gained psychological power which changes interpersonal perceptions and influences an individual’s mental and physical performance". It focuses on the perception of the athletes, or in other words, how it feels to them. Most often this describes a scenario in which something positive or negative happens and the athlete now feels that is more (positive) or less (negative) likely that the next play will go their way as well. I think it is fair to say that most people have experienced psychological momentum before, we all know the feeling of a game slipping through our fingers or suddenly feeling like everything is going your way. The TSN turning point is even based on the idea of psychological momentum.

On the other hand, there is behavioural momentum. This refers to: "the tendency of a reinforce behaviour to persist in the face of disruptors" (Nevin, 1996). This concept is a bit more complicated but I can explain it through an example in football. Before the game, the coaching staff of our fictive football team determined that the key to winning the game is to throw the football as much as possible. They predict that if the teams consistently throws the ball, they will win the game. However, during the 3rd play of the game, the quarterback throws an interception which results in a touchdown for the opponent. This is referred to as a disruptor. Negative behavioural momentum might happen in this scenario if the quarterback is less likely to throw the ball after this play. This can lead to lower performance because he is no longer following the optimal game plan. On the other hand, if that same 3rd play results in a 70-yard touchdown, the quarterback might be more inclined to keep throwing the ball, this is referred to as a reinforcer. An interesting point about behavioural momentum is that the mindset and attitude of the athlete can influence how often this type of momentum occurs as well as how strong the effect is. Not only that, but most elite athletes are actually known for their persistent belief in the game plan and their abilities even when it doesn't seem to be working. A great example of this is Stephen Curry, who will continue to throw 3-point shots even if he missed the last 10 shots in a row. So negative behavioural momentum can be avoided by using mental training.


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Now you know what momentum is, the next question is does it actually influence performance? Many studies agree that psychological momentum does exist in the minds of the athletes, and even that this perception can lead to different behaviour. However, there is no significant connection between any kind of momentum and performance (Moesch et al., 2014). This doesn't line up with what we can all see and feel. We all know that there are periods of the game in which one team is much better than the other, and we have all seen great comebacks. Researchers acknowledge this fact as well and offer an explanation on this point: "Periods of momentum and anti-momentum shift within a match, and therefore render results on a complete match level non-significant. Momentum is not a phenomenon that normally lasts for a complete match." (Moesch et al., 2014). Although momentum exists, it does not lead to a difference in the performance between two teams because the periods of momentum between the teams are balanced over an entire game.

What does this mean for the great comebacks I talked about at the start, are they just a fluke, or could they be rare instances in which the periods of momentum aren't balanced between the teams? I don't think either of those points are what behind comebacks. Rather, the existence of a comeback lies within the conclusion of the momentum research: momentum balances out over a full game. For a comeback to take shape, two things have to happen. First, one team has to take a sizeable lead and second, their opponent has to overcome that lead and win. However, we tend to only focus on the second occurrence and often ignore the first. When you look at both, comebacks are nothing more than a rare occasion in which the periods of positive momentum for each team happen all at once and in sequence.

To illustrate my point, let's go back to the Liverpool FC vs AC Milan game and to keep it simple, we will define a period of positive momentum as scoring 1 goal. Each team has 3 periods of positive momentum (the score after regular time was 3-3). In order for the comeback to happen as it did, AC Milan needs to have all of their periods of momentum in row, to build a 3-0 lead before Liverpool has their periods of momentum in a row to come back to 3-3. If these periods of momentum do not happen in this order, and Liverpool equalizes to 1-1, 2-2 and finally 3-3, we wouldn't be talking about a comeback at all. I understand this is a simplistic representation of a complex game, but it illustrates an important point about comebacks.

Overall, comebacks are simply a precise order in which periods of positive and negative momentum unfold in a game. Maybe, this is a disappointing idea, but I don't think this takes away any of the magic of a comeback. I still get goosebumps when I see that game-winning Patriot touchdown.


Higham, A., Harwood, C., & Cale, A. (2005). Momentum in soccer: Controlling the game. Leeds: Coachwise

Moesch, K., Bäckström, M., Granér, S., & Apitzsch, E. (2014). Hard fact or illusion? An investigation on momentum in female elite handball from a team perspective. International Journal of Sport and Exercise Psychology, 12(2), 106-120.