Technical fouls as a trigger of momentum change: analysis of two decades of NBA data

In an analysis of NBA big data (4,196 cases over 21 seasons; 2000–2021), we examined the effect of technical fouls (TFs) on game momentum. Considering leading or trailing positions in home and away games, we studied performance metrics like points, rebounds, assists, and fouls across immediate, short-term, and medium-term timeframes. Using a quantitative methodology, the results showed that TFs were primarily called on the home team's coach (66.1%) when his team was trailing and the away team's coach (78.1%) when his team was at a disadvantage. Overall, TFs were called in 72.5% of the cases when the team was in a losing position. Furthermore, when the home team's coach was penalised with a TF, the home team secured victory in 44.2% of instances, while the away team won only in 28.1% of games played on the away team's court. Rebounds and fouls were the most pronounced performance indices to change after a TF call. The psychological state, which precedes and proceeds the TF calls, is considered the main reason for the momentum change. By and large, during crises, coaches can prioritise TFs calls, especially in home games, to boost psychological momentum. TFs can initiate team decline and boost scoring by decreasing personal fouls and increasing defensive rebounds. Future research is required to explore TFs’ effects within game quarters and differences between regular season and playoff games for further insights.