In what scenario does a turnover commonly occur?

A turnover commonly occurs when the offensive team loses possession through an interception or a fumble. In football, a turnover signifies a change in possession that can dramatically affect the momentum of the game. When an offensive player throws a pass that is intercepted by a defender, or when a player loses control of the ball while running or being tackled (resulting in a fumble), the defensive team gains the right to possess the ball. This event is crucial as it not only prevents the offensive team from scoring but also provides an opportunity for the defensive team to advance the ball and potentially score, thus impacting the game significantly.

The other scenarios described do not directly relate to a turnover. For instance, the transition of the offensive team to defense does not inherently involve a loss of possession that defines a turnover. Similarly, a player not performing well does not guarantee a turnover, as it refers to player performance rather than possession changes. Scoring a touchdown by the opposing team does not involve a loss of possession from the offensive team; rather, it is a normal scoring play that can happen during a game. Therefore, the specific actions of an interception or fumble are key in defining when a turnover takes place.