Bass = tweener, the bad label
He is like 6'8 that is not good in rebounding, blocking shots, over the rim dunks like a pf. No handles, mediocre passing and needs to be super wide open to hit a 2 pt jump shot , missing qualities of a decent sf. He has decent strength and quickness and that's it.
I wouldn't say Bass is a tweener. That suggests he either has two positions where he is an imperfect fit or zero positions because he fits neither. Bass is a power forward, an undersized power forward, but only a power forward.
I think being multi-positional is a trait that is desirable in bench players, so I think Bass is suited to being a guy who starts but does not finish games due to his flaws, sort of like how Kendrick Perkins was used during his tenure in Boston.
Offensively he is a small forward though. How many post touches has he had recently? All his offense comes from jump shots or face up drives, that sounds like a small forward's offensive repetoir to me.
I have a hard time seeing him as having a SF's offense when he doesn't shoot threes. I could see your point if he made some attempts with a low percentage made, but he doesn't shoot them at all.
I don't see a back-to-the-basket post-up game as necessary in the modern NBA. If I were to replace Bass, I would want a stretch 4 who actually takes (and makes) threes more than I would want a guy who gets most of his offense down low.
Bass isn't incompetent when it comes to post offense and he is an adequate post defender. On defense especially, he is clearly a PF.