I feel like this option has been really underwhelming. I hope Nordeus can do something to improve this.
My personal opinion: The quality growth of a player should not be affected. To be honest you should gain both quality+ special or position.

Like in a season you can either gain one quality star Or a ne special/position.Since you lose a quality rank it is not worth to get a new special/position. The best way to get a special player is buying it with the abilitiy.