I agree that his passing and defense need work if he is going to be succesful with Favors, or just successful in general. Thankfully, Kanter just turned 22, and his passing HAS gotten better each year. Since passing is a team concept, and Kanter hasn't had the luxury of playing with teams as often as other prospects, I don't think we should be writing him off because he started out as a bad passer, but rather we should monitor how the skill is developing.
Kanter has increased is AST% every year that he has been in the league.
https://www.basketball-reference.com/players/k/kanteen01.html
He started out at 1.4 AST%, which was pitifully low, but has since worked that up to 6.4%.
I think looking at Marc Gasol's stats compared to Kanter's is unfair, because Gasol was 24 when he entered the league, is a great defender, had been coached extensively, and had a brother to hone his game with (Kareem Kanter isn't NBA caliber). I think his counterpart of Randolph is still unfair, but more appropriate.
Randolph's AST% has bounced up and down throughout his career, but I think it is worth noting that at 21 (first season above 1k minutes), his AST% was 5.7%. Kanter played above 1k minutes at 20, and his AST% was 5.0. At 21, Kanter upped his AST% to 6.4. Randolph took a big jump the following year, and now his AST% for his career hovers at 10.3%. I think Kanter can easily hit the 10.3% mark once he is developed and more confident in his game.
https://www.basketball-reference.com/players/r/randoza01.html
Kanter can be our Randolph, but w/ a 3 ball. Favors needs to up his D and passing if he is going to be our Gasol. Right now his AST% is at 7.3. Gasol's career AST% is 13.7%.
Gasol entered the league at 24, and posted a 9.7 AST% his first year. Favors is 22. I still believe in the Favors and Kanter duo very much. Randolph didn't make the all star team, or team up w/ Gasol until he was 28. Gasol didn't enter the league until he was 24. Favors is 22, and Kanter just turned 22 as well. Big men develop slower, so sit back and be patient.
https://www.basketball-reference.com/players/g/gasolma01.html
https://www.basketball-reference.com/players/f/favorde01.html