Depending on the player, having him not playing can (I think) also cause a WE drop (albeit more slowly). I know this is true if he plays very little, not 100% certain if he plays not at all. If it is, you could have him slowly lose WE over the full season, then put the RS on at the end only to learn he would have been fine taking it. And, at that point, you cannot recover that lost WE.