I think that for your team you are right. But your team is ranked third in the bb world, making it a very poor test case. There are lots and lots of teams in the low to mid level leagues that have much larger rosters than you do and have more players of similar skill level. For managers of these teams, it is indeed a great chance to experiment with various lineups, tactics, etc. Even if a team's starters have played, the coach can still see the effects of different tactics because of the similarity in skill level of a larger roster of players.
Once I scored a basket that still makes me laugh.