|Fig. 1: Teamgeist Soccer ball. This ball was used in the 2006 World Cup. (Source: Wikimedia Commons)|
While the shape and size of the soccer ball has remained constant for many years, the maker and the specifics of the ball has changed for each World Cup (which occurs every four years) and at each major international tournament a different company is responsible for making the official ball.  To many the difference in the ball is insignificant, but at some events, including the 2013 FIFA Confederations Cup in Brazil, 2008 EURO Cup in Austria and Swiss, and most notoriously the 2010 FIFA World Cup in South Africa the seams of the ball and the number of panels has drastically changed the ball, and the players have noticed. These changes have resulted in some very serious differences in the energy of the ball and the manner in which it moves.
In the past the World Cup soccer ball and the balls used for the other major international competitions were almost identical to the ball that was played with by children around the world. However, starting in 2006 these tournaments have been playing with a variety of very different balls . The regular soccer ball that we are all used to seeing is made up of 32 stitched together leather panels. However, Adidas unveiled the TeamGeist (shown in Figure 1) in 2006 for the World Cup, which only had 14 panels.  After the 2006 World cup there were two different balls introduced at different tournaments with 6 and 8 panels. 
What's most important in a ball's movement is drag, the force that makes it dip and curve in unexpected ways. The smoother the ball, the greater the drag at higher speeds. Furthermore, with fewer panels that are glued rather than stitched together, the more recently designed balls have been getting increasingly smoother. A researcher named Sungchan Hong found that in a wind tunnel the direction that the ball is pointed and the direction the panels are oriented change the drag of the ball. The 8 and 14 paneled balls both traveled more unpredictably because of this phenomenon, curving more or less depending on the orientation of the ball. 
Another major factor for how a ball acts is the altitude. Each ball experiences different changes when played with in altitude. Many researchers and ball designers blame the altitude for the players unhappiness . Since the aforementioned changes players have constantly complained about new balls. Common complaints are that the ball moves randomly, making goalies miss the ball, and that the ball is too easily lifted off the ground, making shots sail over the goal. 
While the rules do not stipulate a certain number of panels that is necessary on a soccer ball, the affect that a different number of panels can have cannot be understated . Many researchers have studied the affects of different numbers of panels and different seams on soccer balls including Rabi Mehta, an aerospace engineer for NASA. Mehta, along with many others found that the movement of the ball is unpredictable and erratic.  Thanks to researchers and our current understanding of physics and energy Adidas and other companies that make soccer balls are convinced they can finally make a ball that is optimal for all players.
© Yale Goldberg. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
 S. Hong and T. Asai, "Effect of Panel Shape of Soccer Ball on Its Flight Characteristics," Scientific Reports 4, 5068 (2014).
 R. Eveleth, "Physicists Say New World Cup Soccer Ball Design Has Big Impact," National Geographic News, 30 May 14.
 G. Brumfiel, "Scientists Keep A Careful Eye On The World Cup Ball," NPR, 20 Jun 14.
 T. Williams, "The Effects of Altitude on Soccer Match Outcome," Massachusetts Institute of Technology, 5 Mar 11.