Re-do the development engine to provide more variation. This should include different patterns of development across ages, and vastly different degrees of development, so that you can't tell easily from looking at a half-season of development how a player will develop. Include some potential for failed and explosive development in each player; ideally, make the degree of risk that a player will not develop (and the reward that a player will super-develop) some sort of rating that you view more accurately the more you spend on scouting.