I'm afraid that's a lot of flaws to overcome and not that easy to fix, reason why he's #44... Watching him, Sidy is just not what you would call a talented player, but more of an hustle transition guy.. As you explained, he can't create for himself, struggles in half court vs. set defense and is not a shooter which is really a problem in spurs ball movement system...He's mostly valuable in transition where he can hustle his way to the rim to finish or for a dime as we can see in his most of highlights.
I truly believe his value resides in defense where he's really versatile thanks his instincts an BBIQ... Then again, developing a decent 3 is where he'll really be able to stay on the floor and be more than an 3rd sting, defensive specialist wing.