The 2020-21 season of the Big Bash League saw the implementation of some new rules in the tournament. One such rule was the X-factor rule.
According to this rule, a team can announce two additional players outside of their playing XI ahead of the start of their match. These players can be substituted for any other player in the XI, but only after the 10th over of the innings. This substituted player can bat, bowl and field. However, this X-factor player cannot be substituted by a player who has already batted or has bowled more than one over.
Only one of the two additional players can be substituted under the X-factor rule and not both of them. The X-factor rule was conceived to give the teams a strategic boost which can turn the match around with the inclusion of an expert batter, bowler or an all-rounder.
Unfortunately, the X-factor rule was not met with positive reviews. As a result, it was terminated by the 2022 edition of the Big Bash League. However, inspired by the X-factor rule, the Indian Premier League (the biggest Major League Cricket tournament) introduced the Impact Player rule, starting from the 2023 edition. It differed from the X-factor rule in two ways:
Instead of two, the team could announce five additional substitutes, of which only one player can be the impact player.The impact player can be introduced at any stage of the innings, unlike the X-factor rule which could be implemented only after the 10th over of the innings. Notably, the impact player cannot be substituted in the middle of an ongoing over.