You won't play the season with the low quality players, you just have them to manipulate the Cup draw. The game decides the competition you will face in the Cup (and Champions League or Super League if you qualified) based on the quality of the top 14 players on your roster. The idea is to release higher quality players before the next season starts (like if they are older and you weren't going to keep them anyway) and replace them with low quality players. That way your top 14 is lower and your cup draw (and CL/SL draw) will be easier the next season, and *then* you replace the low quality with high quality.
I don't do this myself since it feels like cheating (it's not cheating, the rules allow it, but I would rather have the challenge).