I agree you start 5, trust 7 and play 9 or 10 ideally. However, the idea that guys are going to be unhappy not playing is a losers reason to not recruit 15 guys who can compete for a spot. It's coaching...explain the philosophy going in, give them opportunity, talking to them one on one with stats and film explain to them why they are not in the rotation. Work with them individually on what they need to do to get in the rotation. Root for all 15, team first, communicate...guys get it...very important to define and explain their roles right now...circumstances can change that, their improvement can change that but this is where it shakes out right now. Players get it, IF you explain it to them. "We chart 3's every day...you are making 17% of them, these 3 guys are at 47%, 41% and 39%....that's why they are ahead right you." Turnovers, rebounds, defense find something they do better and offer encouragement.
To only recruit the 10 guys who will play means they gotta stay healthy, means you can't have any slumps, and missed evaluations of what the 10 can do. With 15 you can be good...you got guys pushing to get in the rotation who realistically can.
We have four, maybe 5 who are very doubtful to see the rotation. You don't fool players...they know who can play when you got 10 candidates. The top 10 are too comfortable in our situation or they will be soon imo