In 2009, when NASCAR implemented double file restarts they also implemented the wave around rule. The purpose of the rule was to make sure leaders would start at the front on every restart.
Based on the rule, lap down drivers can choose not to pit under a yellow flag while the leaders pit, to gain a lap back. At times this can lead to several cars taking a wave around, under a yellow flag, after getting caught a lap down with an untimely caution. Continue reading