What if the player's best position changes? Can the salary go down because of this (assuming you calculate the salary the week the position changes)?
only when the position changed because of a skill down, as i said the Position showed is the one where he gets the most salary.
Maybe i use your example in a different direction, if you train an SD inside to design a good SF or PF. The first skillups would be pretty salary neutral, until he switch to a SF.