AbstractAs on‐field success is nowadays the main objective of European soccer clubs, good management needs to extract the highest sport success from the squad talent at hand. Because teams differ in their quality, performance needs to be compared with the best practice of comparable units. One remarkable source of heterogeneity across teams is the squad composition, which can produce gains from diversity together with communication costs. The paper studies the efficiency in sporting performance of soccer teams, paying attention to how the number of foreign players relates to productive inefficiency. Using data for 146 teams in the top 5 European leagues during 10 seasons, we estimate a double heteroskedastic True Random Effects Stochastic Frontier team production function. We find that (i) the number of passes, ball recoveries, and shots from the penalty area improve team efficiency, and (ii) a higher number of foreign players increase inefficiency. Our findings suggest that gains from squad diversity might be offset by communication costs.