摘要：Introduction:This study aims to develop a method for characterizingthe offensive playing style of soccer teams, in terms of its ball circulation profile,and respective efficiency,considering the ball circulation outcomes.Methods:Ball circulation dynamics were categorized based on a descriptive representation of ball possession parts (start,ball path and end) and encompassing four variables: team;action or event;pitch partition; opponent defensive penetration degree. The resultant set of ball circulation dynamics encompassed all possibilities of ball circulation on the pitch and were categorized considering the degree of success of the ball circulation lead to a penetration in the defensive system. Hence,there were defined two main classes - incomplete and complete penetration dynamics. Incomplete penetration dynamics are those that do not reach the last defensive line of the opponent defensive system. Complete penetration dynamics are those in which the offense successfully penetrates the ball until the last defensive line or overcomes the last defensive line. Complete penetration dynamics were divided in vertical penetration,indirect penetration and start in penetration. We applied the set of ball circulation related variables to assess nine games from the finalists of UEFA Champions League season 2008-2009,Barcelona and Manchester United (final game,four semifinal games and four quarter final games). An assessment was performed through an automatic identification of game events using a finite state machine (FSM) software that selectively searched for particular classes of coding sequences in the data of ball circulation classes manually acquired from video footage. Results:We identified significant differences between Barcelona and Manchester United in terms ofthe ball circulation style in the classes: i) incomplete penetration dynamics in defensive pitch;ii) long ball kick on incomplete penetration dynamics in defensive pitch;iii) a back-circulation pass on incomplete penetration dynamics in offensive pitch. No differences were found for penetration styles.Discussion:In regards to ball circulation,more than one third of the dynamics from both teams reached the penetration zone of the opponent defense or ended with an effective offensive action (i.e. shot on goal or a cross,without a penetration). Barcelona and Manchester presented significantly more incomplete dynamics,respectively,in the offensive pitch (33.6% BAR and 25.2% MUN) and in defensive pitch (43.5% MUN and 34.9% BAR).Conclusions:These findings provide meaningful variables of ball circulation in soccer that may be used by coaches simply gathering data from video footages.
