Full disclosure, I don't post here much and I became a fan of the Jazz when you guys got Exum and Ingles (Australian obviously). I don't think Exum should be starting over Rubio now, but I am going to make the case that he should be playing more than 18 minutes a game, and he should be given a bit more freedom to try and create in the half court instead of giving it to Mitchell or Ingles and standing in a corner.
The advanced stats support Exum supporters for the most part early on in the season. Looking at general team stats, the Jazz' ORTG when Exum is on the court is 120.4 PPP (!), when he's off the floor it drops to 114.3, good for a +6.1 difference. Rubio on the floor sees the Jazz ORTG at 113.4, and it goes all the way to 121.8 when he's off (!), good for a -8.4. Defensively, the Jazz are at 112.4 when Exum is on the court vs 110.4 when he's off, a -2 difference which leaves Exum's Net RTG at +4.1 when he's on the floor. With Rubio on the floor, the Jazz defense has a 112.5 vs 109.2 when he's off the floor, a -3.3 difference and overall his Net RTG is a -11.7. There's a lot of factors to consider here, such as the entire starting lineup having issues offensively which could hinder Rubio's ORTG for example. The surprising stat to me there was how bad Rubio's DRTG is considering he gets to play a lot of minutes with Gobert while Exum (who I expected to have a negative DRTG too from watching games) is usually playing with more of the bench unit or Favors. So early on in this young season, Exum is clearly helping the team more than Rubio through simple on/off stats.
Other personal stats suggest that Exum is outperforming Rubio pretty substantially too, even if you don't necessarily agree with the effectiveness of a particular stat in general, Exum outperforming Rubio almost across the board should paint the picture. Exum on left, Rubio on right
PER - 14.1 vs 8.9
TS% - 52.7% vs 45.4%
3PAr - 29.1% vs 41.0% (31.3 3pt% vs 32.0 3pt% to qualify that a bit more)
AST% - 16.2% vs 32.9%
TO% - 9.5% vs 24.1%
WS - 0.3 vs 0.1
WS/48 (to account for the minutes difference) - .093 vs .020
BPM - -1.7 vs -3.3
VORP - 0 vs -0.1
Really after looking through all the stats, I'm on board with the idea of Exum not necessarily being the solution to all problems now, but being a much better option than Rubio at this juncture. I don't want to promote Dante's upside as a reason for why he should start over Rubio, because that implies that Rubio has little upside which we know is false from his excellent run post all star break last season, and it's why I think he should still start.
It's clear to me though that Exum should be given the opportunity to have more free reign to learn how to create in a half court setting if Rubio is given the same freedom to refind his form from last season and Mitchell has the freedom to find his form too. Most people here would agree that Exum is probably the X factor for the Jazz' title hopes, as he's shown he can mix it up with the best defensively under the brightest lights, but if his offense can catch up then he becomes a dynamic 2 way player and someone who becomes just as important at Crowder coming off the bench instead of a guy that Snyder wants to play for his defense but couldn't trust to look after the ball at all on offense.