Playing only 6 or 7 guys in most games is not sustainable all season long; that's the point.
While Izzo is worried about developing his 8th, 9th, & 10th players, Boeheim is a hell of a lot more concerned about developing his
starting five to where they can compete with the best they'll face. And after he thinks he has a starting five who are playing reasonably well together, his next priority is to develop his 6th & 7th players, to where--when they come into the game--they'll be complimentary, and not just a cause of mistakes & turnovers.
What all the Deep Bench Fans seem to ignore is the
extreme importance of giving your 1st five, and then your next 2 subs the minutes
they need to be able to develop over the course of the season. If your first five are playing fairly well, then you can afford to give time to the 6th & 7th players. When do you know your starters are doing fairly well? When they aren't struggling to beat a team they're heavily favored to beat. If they're struggling, then they obviously need all the time they can spend together on the court to get better as a team.
And yes, Jim Boeheim will tell you it's important to have some good substitutes who can come into the game with the game on the line and not blow the game on mistakes, and also because of the potential injuries, etc. It is crucial that
the 6th and 7th players get as much time playing with the starters as they can, if they're gonna be any help at the end of the season.
So yeah, when Boeheim sticks with a 7-man rotation, he knows he's rolling the dice on being caught by an injury some time during the season. Of course, he could be overly concerned about that and end up getting the criticism that Izzo's hearing. In his judgment, based on his experience, is that most times he'll be able to avoid catastrophic injuries, or that his 8th guy will be able to step in as the 7th guy in the rotation, without it posing too great a risk to his team's fortunes.
So here's the thing: aside from those concerns, any PT you give to the 8th, 9th, & 10th players is PT you're taking away from your 6th & 7th players (and/or your starters, who also need a lot of time playing with both themselves and with the 6th & 7th players). Why would you do that? Unless maybe your 6th and 7th players are MDAA's, like the starters are?
The time constraints that coaches face are HUGE. They have only so many practices and they see the improvement that occurs via repetitions. So here's my question for the Deep Bench Fans:
Are you willing to acknowledge that what you're really advocating is that the 6th & 7th players should be deprived of the time
they need to develop w/the starters, for the sole purpose of giving more development time to the 8,9,10 players, who are very unlikely to be called upon to help win the tough games later on? Cuz that's what you're calling for, whether you realize it or not.
It's not a "costless decision" to give your 8-10 players more PT. You're taking it away from players who need it just as much, and maybe even more. Do you guys realize this, or no?