His basketball IQ is so low it's pathetic. He doesn't fit BS's offense because he is so.... Dang... Slow... With the ball. He's an iso player who makes the ball stick. It's so frustrating to watch him iso for 20 seconds in slow motion then throw up a brick.
Yeah, that can be frustrating. It probably doesn't happen all that much, however. These things get tracked now. For example, here is the percentage of time on the court each Celtic player had possession of the ball.
Thomas - 21.2%
Rondo - 20.4%
Pressey - 18.3%
Nelson - 17.8%
Turner - 16.0%
Smart - 10.4%
Thornton - 5.5%
Powell - 5.3%
Sullinger - 5.2%
Green - 5.1%
Prince - 4.5%
Bradley - 4.4%
Bass - 4.3%
Olynyk - 4.1%
Randolph - 4.0%
Jerebko - 3.8%
Zeller - 3.8%
Datome - 3.7%
Crowder - 3.7%
Wallace - 3.4%
Young - 2,8%
Wright - 2.8%
Relative to other primary ballhandlers, Turner didn't have the ball as much. This partly speaks to his role -- ideally he's a secondary ballhandler, but because Smart wasn't really ready to run an offense, he took some of Smart's duties. Which was useful.
Anyway, did he chuck up a lot of bricks? Not all that many for someone in his role -- here's pull-up shooting percentage:
Prince - 47.6%
Turner - 41.9%
Datome - 40.7%
Bass - 40.6%
Bradley - 38.4%
Thornton - 35.1%
Pressey - 34.9%
Zeller - 33.3%
Green - 33.1%
Thomas - 33%
Olynyk - 32.9%
Crowder - 31.8%
Sullinger - 31%
Rondo - 30.3%
Smart - 30%
Young - 26.1%
Nelson - 22.7%
Jerebko - 15%
Wallace - 0%
When you look at Turner compared to other primary ballhandlers, and pretty much all of the team, he was a good option to take the pull-up jumper. Is that a good shot in general? No. But that's the shot teams try to force you into, and he was not bad at it.
Finally, it's not like he was taking those shots all the time. Here's pull-up attempts per game:
Bradley - 5.0
Thomas - 5.0
Turner - 4.3
Green - 3.8
Nelson - 3.7 (and he made 22.7% -- talk about offense-killing)
Rondo - 3.5
Thornton - 2.4
Prince - 2.3
Smart - 2.1
Datome - 1.5
Crowder - 1.5
Sullinger - 1.5
Pressey - 1.3
Bass - 1.2
Olynyk - 1.2
Young - 0.7
Jerebko - 0.7
Zeller - 0.1
Wallace - 0.1
Anyway, yes, assuredly there were possessions when Turner got stuck with the ball and heaved up a bad shot. But they weren't that frequent, either with regards to how much he had the ball or heaved up bad shots. Again, teams try to prevent layups and open jumpers -- defenses will win possessions and cause pull-up shots to happen. Turner makes the defense win less often in such instances. If what you primarily remember from Turner's game is the bad shot, you're a victim of confirmation bias.