Basketball Strategy: A Discussion on the Use of the Time Out and Momentum

And that's how it ended.....Carolina went on a 6-0 run to finish the last two minutes of the game.

During the game thread, there were a couple of questions and comments about Halmiton's use of the time out and his strategy down the strech. The follow up thought was what impact does the time out actually have on momentum in a basketball game In some cases, it can be distastrous, just ask Chris Webber. We all wondered, why did Hamilton call the time out at the end of the game, would it have an impact on the game? In order to understand the move I started looking for any data or discussions about momentum, time outs and the impact of each on a basketball game. 

Momentum is defined as force or speed of movement; impetus, as of a physical object or course of events and orginates from the Latin word moment. It's roots orginate from Ibn Sina when he described an impetus as being proportionate to weight times velocity. Are you having high school physics flash backs? Stay with me here, I'll get to back to sports soon. Then through a series of interpretations, we arrive at Isaac Newton's explanation. He proposed the idea of quantitas motus or "quantity of motion" as "arising from the velocity and quantity of matter conjointly." He then continues to describe a mutatio motus or "change of motion", that is proportional to the force impressed, he is generally taken to mean momentum and not motion.

Momentum has to physical qualities: mass and the velocity of an object in a frame of reference. The equation is as follows:

where p is the momentum, m is the mass and v is the velocity. If an object has a mass and it is moving, it has momentum. However that movement can be changed by an outside force:

or just simply

where F is understood to be the resultant. Therefore, an outside force can change momentum. As the final part of nasty physics, remember the conservation of energy mass and all that stuff....In an isolated system, with two objects (say two basketball teams) the change in momentum in one object must be equal and opposite to the change in momentum in the other object. If you're really interested, you can go here, it's from the high school that Jon Sheyer attended. 

Momentum in sports fits a similar picture: one team takes control of a game resulting in a net positive difference for them and the other team loses control, adhering to the principle of conservation of momentum. When one team is doing well, or has momentum, the other team is typically struggling or trying to find a way back into the game. Imaging a football team that drives 95 yards to score a touchdown, the basketball team that goes on a 10 run to start a half or the baseball team that starts hitting single after single after single. As fans, we get the sense that the wheels are falling off the bus and we only hope something, an outside force (F=ma), will stop or change a team's momentum.

Is there such a thing as momentum in sports? Is it quantifiable? Is it just a perception without quantitative results? Suprisingly, there is a significant ammount of data about this in the medical literature, specifically in behaviroal sciences journals. In 1988, a group of investigators generated a model that explain momentum in sports: Antecedents-Consquences Model. In that model, the authors propose that the perception of momentum is influenced by situational (situation contro, crowd behavior, task difficulty and game importance) and personal (skill level, anxiety,motivation) variable. This model was not only designed to study players, but to investigate crowd perception as well. Some studies have found that certain game actions, such as turnovers/steals/crowd noise, seem to be associated with beginning, maintaining and ending momentum. In one particular study by Burke et al (1999), found that during a period of positive momentum, a team only scored on average 5 more points than their opposition.

One study that I found interesting was the following: The authors took 8 individuals who had some understanding of basketball and they had them watch 12 NCAA Div 1 Men's and Women's Basketball games in person. These individuals then recored when they felt the beginning, middle and end of a perceived momentum period occurred. During the 12 games, there were 89 periods of perceived momentum. The most common starting event of those periods was a three point shot. The next most common were a caused turnovers, a lay-up, a steal, a jump shot and then a defesnive stop. The most common events during an period of perceived momentum were a caused turnovers, a layup, a three pointers, a defensive stop and then a jump shot. The events that caused an end of a perceived period of momentum were a time out and the positive momentum team causing a foul. They concluded that most initiating events of momentum swing were a positive performance by the momentum gaining team. There are a ton of confouding variables in this study, but there was a lot of intra-observer agreement in the events that started and ended periods of perceived momentum.

Other studies have confirmed that there is usualy the presence of a positive even that leads to a swing in momentum, rather than the absence of such an event. One study looked at the events leading up to a perceived change in momentum, specifically looking at the rate of positive events in the 3 minutes prior to a perceived change. The higher the number of posiive events, the more likely a team is to have a positive momentum change. Essentially, they demonstrated the notion of positive reinforcement. They also looked on the impact of the time out on this positive reinforcement model and found a significant difference in length of momentum swing depending on the time at wchich the time out was taken. They found that in a period of time leading up to a time out, a team that was on a positive swing, averaged 2.63 positive reinforcement ratio (so the number of good things they do to the number of bad things their opponent does). In the 3 minute interval after a time out, the reinforcement ratio dropped to 1.11, so almost equal. To these authors, from the Universiy of Pennsylvania, Rutgers and New Hampshire, a time out was an effective method to stop a momentum swing. Other studies argue that a coach must determine the reinforcement ratio prior to calling a time out: how much are they out scoring you by? What is the turnover situation? Are you still geting turnovers? Then, when the time out is called, you must determine how to counter those reinforcement occurrences...do you need to put in a shot blocker, do you sacrifice defense to substitute your three point shooter?

I lifted this list from coachingtoolbox.net about possible positive and negative events that may cause momentum swings:

Momentum Getters

I really like this list as it encompasses all of the events that we either cheer and get that sense we're on a roll or bury our face in our hands and wonder how our team could be so bad. For example, you're up by three and Danny Green steals the ball and has an open lay up...you foul him and he gets the and one....why? Either foul him so he doesn't make it or let him have the basket, you're still up by one and the clock is ticking. Momentum killer.

This is an interesting article from slate.com that talks about the use of the timeout in the NBA. The time out in basketball is an interesting concept. Think about when time outs are called in other sports. In football, it is typically for clock management or bad matchups, or the play clock is about to expire. In hockey, it's around face offs, not during a play. In baseball, a batter may call time in the middle of a pitch sequence to get a pitcher of his timing. But in basketball, you can call a timeout as you fall out of bounds to maintain possession. You can call a time out in the middle of an offensive set to prevent a 5-second call (NCAA only) or to call or design a play.

Against UNC, we had the ball with numbers coming down the court with only seconds remaining in the game. The crowd was raucous and UNC was on their heels. Hamilton called a time out. There was plenty of time left on the shot clock. Their defense was tired. Our guys were geared up. We called a time out. It killed our momentum. We lost the advantage. It allowed UNC's defense to get set, allowed their guys to catch their breath and figure out how to win the game. This was an instance in which a time out was taken by the team with the perceived momentum. Unfortunately, it followed the models described above...we didn't score. We lost the game.

Time outs are an effective way to slow a teams momentum. How many of you have been watching a basketball game yelling for the coach to call time out? We have all had that sinking feeling of watching our opponent hit shot after shot-- positive reinforcement.

That perception of momentum is real. It is even real in players. One study looked at competition between two players shooting free throws. The first player to get 2-3 won. They surveyed the players after each round. In general, the person who won the round was confident that he would win the next round and in most circumstances that player did. Players sense it, coaches sense it and fans sense it.

There were many reasons we lost that game against UNC. Unfortunately, an ill timed time out contributed significantly to the loss. Next time you watch a game, keep track of when you feel momentum is starting to change. What is the team with the momentum doing? How did the momentum swing start and what ended it? I bet, more often or not, it will be a time out or reckless foul.