Space definition for match analysis in soccer

Studies on match analysis in soccer frequently use some kind of geometrical field division in order to situate and classify the actions observed. However, as an invasion game, with both teams acting in the same regular space, intertwining and creating play configurations of outstanding complexity and dynamism, a more appropriate procedure to locate actions encompassing its tactical meaning seems to be in relation to opponent distribution in the field. Aiming to provide a contextual notation of actions, this paper proposes the utilization of a match analysis instrument based on the opposition’s spatial configuration called Space of Defensive Occupation (SDO). SDO emerges from the application of the concept of space effectively covered (Merand, 1976; Gréhaigne, 1992) to the entire team while defending. Apart from peripheral limits, the position of players inside the SOD is also considered, resulting in internal subdivisions and generating different zones. For the purpose of studying the relationship between the actions of assistance pass, reception and shot and SDO zones, we have analysed 112 shot attempt situations from seven matches of Brazil and Germany in the 2002 World Cup. Variables were classified into four groups:(1) zone of action’s occurrence – frontal (F), central midfield (cM), peripheral midfield (pM), central defence (cD), peripheral defence (pD), central space behind the defence (cB), peripheral space behind the defence (pB);(2) action – assistance pass, reception and shot; (3) shot attempt result – successful or unsuccessful;(4) team – Brazil, Brazil’s opponents, Germany and Germany’s opponents. Chi-square tests indicated that cD is proportionally the main reception and shooting zone, while cB and pB presented the highest relative efficiency. cM and pM are essentially assistance pass zone, though cM’s relative efficiency is specially low. Both of these showed the smaller relative efficiency to reception and shot. For the assistance pass, cD is the most efficient; conversely, there is no significant difference between successful and unsuccessful distributions among SDO zones. According to the spatial distribution of actions related to successful shot attempts, assistance pass was most diversified and unpredictable (J=0.94) than reception (J=0.83) and shot (J=0.76). Brazil played a larger proportion of assistance passes in central zones with reception in central zones than Germany, and a smaller proportion of assistance passes in peripheral zones with reception in central zones than its opponents. Germany did not present significant differences compared to its opponents. The instrument’s reliability was tested with values ranging from K=0.73 to 0.90 for inter-observers test and from K= 0.83 to 0.93 for intra-observers test. The analysis of results suggests that SDO is a reliable instrument, capable of spatially characterizing actions so as to point out differences in team performance.