Shedding some light on in-game formation changes in the German Bundesliga: Frequency, contextual factors, and differences between offensive and defensive formations.

This article investigates the frequency and contextual factors of in-game tactical formation changes, as well as differences between offensive and defensive formations, in professional soccer matches from the 2020/2021 German Bundesliga season. The study found that teams changed their tactical formation during matches in 29.6% of cases, predominantly in the second half, often following substitutions and when trailing in the score. Additionally, offensive and defensive formations differed in 25.3% of the analyzed cases, indicating tactical flexibility. The findings suggest that future research on soccer tactics should account for in-game formation changes and distinguish between offensive and defensive formations to improve methodological accuracy and practical relevance. Coaches may also use these insights to anticipate and respond to opponents' tactical adjustments during matches.