The initial point is fair if the prime signings are so good that the fillers are indeed fillers, then why sign them at all ?
However what appears to be happening is that the 'prime' signings and the fillers are merging so what we appear to have done is sign less quality overall.
That being said 1 in 4 is an overall statement, but its probably on a downward trend, 15 players were brought in season 17/18, am struggling to pick anyone else than GMS who signifcantly improved the team that season.. Devlin was recruited but will count him for next season.
8 have came in this season again , Ferguson aside( i think he is starting to regress, not his fault) so add Devlin , so in 2 seasons 23 players brought in 3 have 'improved' us .
Thats isnt good enough