Have you tested the player? Has he performed well so far?
It is better to put the 40 skills points in the attributes. If you still want to use the accumulated points for something else, then go of an extra position. For e.g, if the player is left footed, add DL; if the player is right footed, add DR. If the player likes to go forward (based on match comments), add MC or DMR or DML. Some users recommend to test the player in the new position before upgrading.