While I empathize with frustration that Dante Exum doesn't currently have either the minutes or the role many think he should have, I'm even more frustrated by many fans' insistence the situation is a product of coaching incompetence, or deceit, or some weird form of nepotism from Quin Snyder's Atlanta days. I really, really struggle to see that point of view.
So here are a few genuine questions that I feel someone with such a perspective has to be able to answer to justify the argument. I'd appreciate answers to the questions, particularly from those most suspicious of the motives for the minutes distribution.
1) Do you really believe the Jazz are currently more competitive, meaning right now, with Exum on the floor rather than Mack?
Consider that the team has been outscored by 82 in Exum's 431 minutes while they have themselves outscored opponents by 53 in Mack's 452 minutes. That seems pretty clear to me and really hard to argue against. This is especially true because Exum's most common two-man lineup pairings are Rudy Gobert and Gordon Hayward, and Rodney Hood is fourth. Mack, on the other hand, shares more court time with Trey Lyles than any other player, and Joe Johnson is his third most common paring.
I simply do not see how the data can be interpreted as to say that Exum is helping the team win games more than Mack, even if we take into account the assistance they get from other players while on the court. Exum is playing with better players more often than Mack and yet the team is still routinely being outscored with him on the court.
How is it even rational to argue that Exum is helping the Jazz win more than Mack?
2) Can anyone who has actually watched numerous games claim that Exum isn't an offensive liability in how defenses scheme with him on the floor?
If you've watched games, you've seen that smart defenses play Exum the way smart centers have played Gobert out on the perimeter, or how Scottie Pippin played Greg Ostertag in the finals - which is to say simply don't guard him at all. Instead, they dedicate his defender as an interior rover or help man who only shifts to Exum on the drive. This problem is only compounded when he plays with Boris Diaw, as smart defenses don't guard him on the perimeter either. The result is a horrendously congested floor for Hayward and Hood.
Again, this is apparent in two-man lineup data (points per 100 possessions).
Exum + Hayward = +0.7
Mack + Hayward = +17.3
Exum + Hood = -4.2
Mack + Hood = +6.2
It couldn't be more obvious in either the numbers or to the eye test. Put bluntly, even if Exum and Mack are roughly comparable players in overall current ability (and advanced stats show both are pretty mediocre though I would say Exum is slightly better individually), Mack could easily be the better competitive option purely on how defenses scheme against him.
When the Jazz play 4 on 5 offensively with Exum on the court, it forces him to shoot them out of the strategy. In games where he's taken 3 or more threes, the team is 4 - 7. When he takes 2 or fewer, they are 8 - 2 (plus they won his lone DNP-CD). He's shooting 28% from three overall, 30% on open shots, and 26% on wide open shots. He simply isn't equipped to punish teams for how they play him given his current jump shot.
If I were defending the Jazz, I would let Exum and Diaw shoot wide open jumpers every time down the floor and I'm confident they couldn't beat me. Other teams are doing just that and I suspect any reasonable person would as well. It's just too obviously effective.
How can anyone actually watch these games and claim offensive spacing isn't drastically hampered by Exum's presence on the floor?
I think the win now versus develop to maximize the future debate is legitimate and constructive. I also think there is ample room to argue the individual merits of Exum and Mack as players at this point in their respective careers. But I do not see an evidence-based position from which to argue that there isn't a clear discrepancy in Mack's and Exum's relative abilities to help the team win games now or that the discrepancy favors Mack.
Without a sound argument on that count, any assertions that Exum's current role is the product of stupidity, favoritism, or neglect simply don't hold water.
Is there something I'm missing?