Because although he's a very good halfback, he could be an even better 5-8th. The player he is most similar to in terms of overall strengths is Fittler.
From halfback he isn't getting as much chance to use his big step and acceleration with a bit of room to move. Also if you think back to a lot of our tries and line breaks so far this season, a significant proportion come from the few times Mullen gets a bit wider and is making the "last play" if you will i.e. dummy half passes to someone who passes to Mullen to either hit one of his outside runners or put the kick in etc.
I think his talents are being wasted playing a traditional halfback role of either shifting it wide, playing it short to the forwards, or kicking. I would much rather see a genuine halfback feeding him good, quick ball so that he gets it in space with options like Simpson, Doogs, Kidley running off him.
Well said K-Man
I can't put the case for keeping Mullen at 6 better than you have already done. So I wont attempt it.
In regard to Walsh's size to play at 7 to Mullen at 6. He's been playing League for a long time at 7.
I'm sure, no I know, he has played against big boys in the lower grades & I have no reason to believe he can't do it in FG.
Give the guy a chance to prove himself. I'm sure Brian Smith will.