The difference between "solid" and "erratic" in a half at NRL level is really only down to how much risk they are prepared to deal with. Obviously skill comes into it more as more risk is taken on.
Cleary and Moses provide a classic example of that, Cleary is "solid" because his game is risk averse. Moses is "erratic" because he is a risk taker.
Moses will only become an elite half if and when he finds the balance between his level of skill, and the level of risk he takes. So he either hones his skills, or takes less risk. Or perhaps a combination of both.
Of the two though I know which one I'd prefer to watch, and it aint Cleary.