you're doing an analysis on incomplete context. Turner was signed as a ball-handler/play-maker. Nurkic wasn't. One of Nurkic's primary jobs is to set screens. That's not a primary job of Turner
but diving a little deeper into the numbers:
* Turner had 283 assists and 114 turnovers. A 2.48 assist/turnover ratio
* Nurkic had 233 assists and 168 turnovers. A 1.39 assist/turnover ratio
* Turner had 108 turnovers from ball-handling and bad passes (6 from offensive fouls). That left an adjusted assist/turnover ratio of 2.62
* Meanwhile Nurkic had 51 turnovers from offensive fouls and other (4). That left him an adjusted assist/turnover ratio of 1.99
yes, Turner was still better but the differential wasn't as big as the numbers would indicate
More then that, Nurkic operates a lot more in the paint than Turner did. He was making passes from there and he was making moves and pivots from there. When he has the ball he's in a part of the floor that's naturally higher in turnover rate. Meanwhile, in the Stotts offense, Turner is moving the ball around the perimeter a lot more than Nurkic and that's a lower turnover area that results in easier assists. Often, when Nurkic is on the perimeter he's attempting screens. That's why he had 6 times the offensive fouls as ET
http://www.82games.com/1819/1819POR.HTM