i haven't looked at your team, but you have a number of options. this requires you think / plan by the week.
1) On friday, take a look at your weekly schedule. separate the games into close/must win and not going to be close (either defeat or win).
2) your hotshot guard starts / plays the close/must win game. 48 minutes.
3) your less-than-capable starts / plays the other games. if you have the starter coming off the bench, depending on the differential in talent, he could play as much as half the game; more likely, you could pencil him in for 12 - 20 minutes.
4) judging from your level, you probably will not make a long run in the Cup. this frees up the scrimmage for training -- which you use to close the talent gap between your starter and your bench as quickly as possible. a better bench gives you more options going forward.
5) you may or may not be at the point where you are starting to win by large margins against weaker teams in your league (maybe there are a couple of bot teams). a nice little trick here is to put your bench player as both "starter" and "backup" and place your starter in the "reserves" part of your lineup -- your coach will play (probably) play your bench player for around 36 minutes and your starter will get the final quarter. combine that with #2 above, and you have handled the weekly minutes for your starter quite nicely.
6) but the best solution -- either via the TL or training -- is to have a player(s) of equal value that you can rotate starts with your current hotshot.