This seems a little like criticizing Trae for having zero dunks. Polla is a true freshman, playing in a new country, and averaging two minutes a game. Looking at his assist numbers in those circumstances and concluding that they mean he isn't skilled enough to contribute down the road is absurd. I have no idea how his career will pan out, but I think he handled himself well on the two occasions (Wichita State and KU) that he played meaningful minutes against a good opponent. As a third string big who only plays when Lattin and Muni are in foul trouble or playing terrible, his role this season is to rebound, defend, and be physical. We aren't asking him to be Marc Gasol or Blake Griffin and help facilitate the offense with his passing.
I have no problem with him being a 3rd string big man who plays minor minutes in favorable situations. That was not the question asked in the OP though.