Trying to understand Watts' mental application in a game is confusing but I find it stems from his basketball excellence.
The main reason he does not chuck himself at the ball (in the air or on the ground) is because he makes the choice of keeping his feet in every contest, even if that contest demands that he fling himself at it. The same principle exists in soccer, where you rarely fly in with a bold tackle. You sit 1 - 2 metres away and keep the opposition player from being able to attack where they want to. Jack often appears to be controlling a space, or hanging back to defend a space, but rarely chucking himself in to get the ball. This surely can be taught.
Also, his brilliance in the 2008 under age championship where he caught the eye of all the recruiters were - this is fair dinkum - his pack marking and goal kicking. Because the defensive pressure is underage footy is poor, he was able to run and leap over packs without physical pressure being a hindrance. Neither Bailey nor Neeld have been able to help bridge the huge physical gap and he still plays like an U18 footballer.
His tackling really is woeful - but I firmly believe this can be taught. Give him a KPI of at least 4 tackles (that stick) a game and see if this changes his understanding of physical contact and going hard for the ball.
It is his pack marking / contested marking that is the main worry. Out on a lead no problems. But jostling and pushing off, blocking for others, steady core strength all seem to evade him constantly so he goes back to being 1 -2 metres off every contest waiting to respond to a play rather than making the play.
Having said all that, I am still in the 50/50 mindset with him regarding trade or not.
One thing I will say. When he gets the ball in his hands his decision making and skills are sublime. Best kick at MFC since Trav Johnston. Just wish he would go and get it more often and make the play.