This article deals with the optimisation of the sport leagues product thanks to adequate rules. It features a new model called intra-championship competitive intensity which measures outcome uncertainty and reversals in the standings of a sport league. The model depends on the league product design and, in particular, on the number of sports stakes in the standings. Intra-championship competitive intensity was calculated in French football Ligue 1 (league without playoffs) and basketball Pro A (league with playoffs) over the period 2004-2009. The results show that Pro A intra-championship competitive intensity surpassed Ligue 1's, whereas the latter benefits from a better competitive balance. Then, we propose a product design which maximises intra-championship competitive intensity and marketing and sponsoring efficiency in the European context. This design needs specific marketing actions to be optimised.