It would be nice to be able to set you mop-up time lineups. Sometimes the mop-up substitution logic is questionalble:
http://www.whatifsports.com/NBA/boxscore.asp?GameID=7463259&nomenu=1&teamfee=9.95 (In this game, why did the Sim put Hoiberg [2.26 mil] into to game in mop-up when Barry [787k] was available. Those 6 minutes
Also, in the past (and maybe again in the future) I have carried some high-minute-high-usage players that I considered to be the worst player on the team, but, of course, needed their usage. My druthers would be to have played them during mop-up time inspite of the fact that they were also my starter.
I like to carry players specifically to play as many mop-up minutes as possible, and when your mop-up player does not play during mop-up time it is very frustratrating, and can cost wins and losses as well. In the example above, I think Hoiberg is a much better player than Barry. If Barry had played I would have 6 more minutes available for Hoiberg to play today. If I lose by 1 or 2 points today...
Automatically taking the player listed 4th on you depth chart during mop-up time, and the ability to add a player to the dept chart 2 times for the same position if one of those times is 4th on the depth chart would fix this problem.