I think One Brow has nailed point#1: It is a matter of timing of the facets of practice and real-game maturity. Anyone who has played sports competitively sees that practice comes before game experience.
Yes, and it has been pointed out that Fes was showing development in practice, and Sloan still didnt' play him. To show your point, you have to explain how playing a player in one game and then NOT playing him AT ALL for 5 or 10 games or more is development. The superior strategy is to find developing players time on the court when it is not likely to hurt (or possibly will help) the game outcome. Sloan did not do this. Repeatedly.
How much practice goes in for a golfer (easist to see for me) compared to game time? Why does Derek Fischr tell CJ "I have to hit 30 three's IN A ROW - AFTER formal practice" in order to go home. I think IGS would agree with this point. The point of the questoin is whether Fes proved himself enough to play in games. THEN game time experience is valuable. This year Fes looks worthy for this consideration.
Fes proved himself enough to play in games by playing in games.
Point #2 is that Sloan has a STRATEGY of keeping regular rotations more than he does 'in-game' hence IGS primary issue (If i can speak for IGS...

Jerry has said over and over and over that we do it as a team. And so the system has to be working to win (compete.) So Jerry favors continutity, stability over in-game adjustments. This is the reason that Tree Collins played as much as he did becuae he would play within the system allowing the WHOLE team to benefit. I bring up that 'yukky' example to illustrate that Jerry does this plan with full understanding, full awareness. Whatever anyone here sees Jerrry and coaches see as well and usually just make a trade-off decision that goes the other way. This is Jerry's strategy; not his ignorance.
Jerry might be fully aware of his lack of adjustment of lineups to what is going on in a given game, but that doesn't mean that it's effective.
And it is absolutely laughable that you are using Tree as an example to prove your point. Even after Collins had years of experience (including the minutes) he was not necessarily benefitting the whole team to play out there. Collins is yet another example of a player whom Sloan overrated and played too much because of Collins' demeanor (and maybe work ethic and maybe practice; I don't have evidence of that). You are totally walking into my argument if you are using Collins as an example of Sloan's decisions working well.
Point 2a: Jerry keeps his main rotation in the game often "too long" becuase he wants that group to get full team/system rhythm. At that point the game time activity is the 'practice.' So there is a decision to be made between "do i put Fes in and get him game time minutes, or do i let the main rotation players continue to run the offense and play the team defense?"
It's more than that, though. Almost on a nightly basis, Boozer and/or Okur would dog it on defense, which hurts THE TEAM, and Sloan didn't bench them. And sometimes Boozer would be in foul trouble late in games because Sloan didn't manage the minutes, and that made his defense even worse. Again, I'm talking 5 minutes per half on average. Oh, and I was also suggesting that last season, those minutes would most likely come from Millsap.
This is why you see Jerry sometimes double down on post players who seemingly don't deserve it. He's playing/practicing for the LONG HAUL as Hopper has noted. Wes Mathews was good enough and disciplined enough to be part of that rotation without screwing it up. The one time jerry made an example out of the team was the Dallas game early last year when he had MEMO guarding Dirk one-on-one and Dirk scores 30 in the 4th (or there abouts.) We all passed out at how senile Jerry was and his blindness and etc. Well. Jerry is not blind. He saw it and asked if the team was ready to get on board iwth the team defense. Or would they like to try to d-up the other guys one-on-one?
LOL. Your example to prove your point (and perhaps cost the team a victory) is when Memo failed?? And you're trying to defend not putting in Fes because he'll hurt the team (when more often than not he didn't)? Think more carefully before you craft your claims; you might be contradicting yourself.
Point 3: Jerry can make an example of Fes with little or no chemistry backlash. So if he thinks Fes is jackpotting, then bench him and this has little or no effect on team chemistry. If he thinks Boozer is lazy on defense, and ponders to bench him, then he has a big dilemma on his hands. Sitting boozer for some manner/level/idea of jackpotting and the whole team is in turmoil becuaes Boozer would rip the situation apart. Remember: "... I'm a STARTER!!! ..."
And you think that sitting Boozer for 5 minutes is going to "rip the situation apart"--more than his matador defense? Your logic is worse than Sloan's. You and others are so focused on players jackpotting around in practice when that has far less to do with the team's success than players who are jackpotting around in games. Boozer would do that regularly on defense, even in his contract year. Memo looked like he was trying harder, but he simply didn't have the agility, which is exactly what some JazzFanz are unjustifiably arguing as a reason not to play Fes, when in reality Fes is more agile than Memo and needed (and still needs) most the on-court experience to reduce the turnovers, cut down on unnecessary fouls, and be in the right spot on offense.
He has chosen a core strategy and sticks with it, which all good organizations do. The financial, statistical, historical evidence proves this is good plan. (Cue the 'ring count' argument here...)
I don't need the ring count argument if Sloan was doing everything reasonably possible to maximize the team's effectiveness. I point to multiple games every year that have been lost because of lack of controlling the paint, usually against teams with above-average size (which Millsap has an especially tough time with, as shown again last night) or speed (which Okur and, to a degree, Boozer had trouble with).
What Sloan does well: instill a sense of work ethic and team play. What Sloan does not do well: adjust lineups and in-game strategies to address what is going on in a given game, and develop players who are not already self motivated (and thus who would probably develop well without him).