He's just 21 years old and has had barely any time to develop.
Moore is a rookie and will turn 23 next month but is light years beyond Bradley when it comes to being a polished NBA player. He doesn't look like he has anything close to Bradley's athletic gifts but he also doesn't make the astonishly awful plays that Bradley does.
The issue is that Moore is pretty much a developed player at this point, and is not a NBA rotation guy almost entirely due to his lack of athleticism/size. He's got a good SG game in a body that can't hack it at the NBA level.
Bradley is still raw but if he developes (and who knows if he will) can be an NBA guard.
By saying that Moore is a "developed player", you seem to be indicating that he has less room to grow than Bradley, and I dont see why you'd assume that. I dont see why any rookie would be considered anywhere near their full development. Age really has very little to do with it to me. You dont get better or more developed due to age...you develop due to experience. Both players have probably been playing basketball for about the same amount of time. Its not like either one just started recently (like Biyombo), and it's not like one was a pro since 13 like Rubio. One played more in college, one played more in the NBA. Given how different the NBA is from college, Bradley has the upper hand there...So far that experience hasn't shown him to be any better than Moore.
Bradley had 1 good game, and people are saying we play better when he plays? Is everyone forgetting what he looked like the last 10 times he played? No one ever questioned his athleticism (which is all he really showed). It's whether or not he can run a half court offense, guard bigger/stronger players, and shoot. None of that was answered last game. To take a bit from Jay-Z, he's got a 1 good game in every 10 game average, and thats so...LAAAAAME lol