But that doesn't make sense for a number of reasons. Firstly, who says what a teams strongest XI is? It's a matter of opinion. Secondly, weakened teams are occasionally fielded elsewhere, and it gives the reserves match fitness, good experience and is useful for the manager. Thirdly, why not put out reserves? Arsenal put out their youth, and still normally manage to get to the semis. They are more than a match for most teams. Also, if it doesn't pay off, it is only a loss to the club, no one else.