Remember the 2010 World Cup Jubalani soccer ball? It was controversial because of its tendency to wildly swerve through the air and becoming the bane of goalkeepers’ existences. The reason? It was too damn smooth which left it susceptible to wild trajectories, as Hackaday discussed:
The problem came down to a phenomenon known as “knuckling.” This happens when the ball is travelling through the air with little to no spin. At a certain speed, the seams on the ball tend to interact with the airflow, channeling it such that it creates sudden and unpredictable movements. The term first developed in baseball, but became relevant to football with the development of the 2006 and 2010 World Cup balls, which suffered this phenomenon more often in play.
The phenomenon became so well known that NASA scientists took the opportunity to throw World Cup balls in a test chamber to demonstrate the effects at play. Knuckling behavior tends to peak at a certain critical speed, with the effect lessened either side of the peak. The problem was that the smoother designs were “knuckling” at higher speeds than balls from previous generations. NASA researchers found that the Jabulani would undergo unpredictable flight due to knuckling at speeds of 50 to 55 mph—right around the speed at which professional strikers can deliver a ball to the net. Meanwhile, more traditional 32-panel balls tend to see a peak in knuckling around 30 mph. Since strikers were typically kicking beyond this speed, knuckling—and thus unpredictable flight—wasn’t such a problem with the older designs.
I personally prefer the classic B&W hexagon-pentagon panelled balls because you can’t beat a ubiquitous design. Honourable mention to the orange balls they use when it snows.