It is a very rare week that Smith scores less than 60 points. Basically the only reason he wouldn't is injury or if it's an Origin/bye week. The others are more up and down. Yes they can go bigger, but they can (and more often than not do) go a lot less. To sum up, Smith is the safe option, the others would be if you wanted to risk it.
smith! and bad move on getting parker.. scores gonna drop without kicking duties and i doubt gallen will play the 80.
