I don't think Rubio is your best example as he can finish at the rim (0.588 this year vs Ant's 0.444 this year). Even in earlier years when he had a low efficiency around the rim, he's always drawn a lot of fouls - free throw rate of 0.391 vs Ant's anemic 0.118. He's also an aberration, a total magician with the ball.
Same thing with Marcus Smart. He has a career FG% at the rim of 0.548 (one year was an incredible 0.694) vs Ant this year 0.444. Plus he draws 4.1 FTA vs Ant's 1.7 per 36. Ant's low efficiency is even inflated because he's highly selective with only 8% of his shots being at the rim so an abnormally high portion of them are uncontested. Boston also has much more motion in their offense creating assist opportunities off the ball. But yes, Smart has an incredibly high assist rate for someone who can't shoot. One of my favorite players.
I don't know much about the other guys you mentioned. I'd have to watch some of their games. My bottom line is I don't see Ant getting assist opportunities and then failing to connect on them. I see him getting not getting assist opportunities because (1) he can't create a threat the draws defenders (2) Blazers offense does not create assist opportunities off the ball either. Ant catches the ball and passes into Melo for a post up. Ant catches the ball and passes to Hood for a post up. Ant catches the ball and it's his turn to create. He could get past his guy but then he sucks so bad at finishing that the defense plays the pass, and all of Simons' focus is on trying to finish. As a result he's mostly given up altogether on driving the ball, it's all step back 3's, which makes it even harder to get assists.
I agree, Ant is not very good right now. But he's quite a bit better than he was last year, so I still have hope. I see him making a concerted effort to move his feet & stay in front of his guy, but he's still too much of a lightweight to bother the shot when a guy backs him into the paint. I see him grab plenty of rebounds. I see he's an efficient scorer despite getting no boost from drawing fouls. I see he can beat his guy off the dribble, but he can't do anything with it.
As far as his passing, I've just seen random situations where the rare opportunity is there and he makes an impressive pass. Not an, "oh I finally see you now" chest pass to a wide open guy. Quick, up from the dribble, threading, Nash passes. Rare yes, so you could say I've seen flashes. He did have 9 assists an that game vs the Kings where he scored 37 points.