Well, I question your notion that substitutes have been deemed not good enough. I also wonder why clubs would handicap
themselves by not having a regular match option for senior squad players who are not usually used in the first eleven
but will be required from time to time.
Maybe the U23 restrictions should be scrapped and the old reserves rules brought back. That would mean that all the players
would share game time around and clubs would surely benefit from that.
And pundits are always telling us that work in training is no substitute for match fitness, so I don't see how Tosun can gain
much from it if they are right.
You can only have a set number of over-age players in the U23's matchday squad so it's inevitable that you can't give all older players game time there. And why clog up a development team with players you've decided aren't good enough and who will probably just go through the motions there with no benefit and could conceivably cause unrest outside the first team squad?
It seems that the U23 team is perceived as a punishment unless you're there to get back up to speed after an injury. The entire point of Niasse's spell there was seemingly to humiliate him and force him out of the club. Him rising above such pettiness and working hard was very much the exception.
As for Tosun then it may be seen that concentrating on working with the 1st team and getting familiar there is of more benefit than expending energy and risking injury at a much lower level of football.