Long term, I feel it's a defensive midfield role or bust for Jack.Speaking of things SOS related...
I like JSOS to the backline.
He lacks the speed and agility to get separation in the forwardline. Lacks speed and endurance to be a full-time mid.
What he does have is footy smarts, he reads the ball well and plays with desperation. He has shown good defensive nous during his limited time spent tagging. He has good vision, nice skills too and can kick to advantage.
I think he'd be a good 3rd tall in the backline (as long as he's not playing on super quick players).
Granted he is competing with Plowman, Marchbank and Doc for that role of 3rd tall/defensive sweeper. But I think backline is what best suits his strengths and most hides his weaknesses.
Unfortunately he's relatively slow, isn't a great user of the footy, isn't exactly powerful and can be prone to fumbling, unfortunately I feel he'd be a liability down back, hopefully I'm proven wrong but from casting an eye over opposing forward lines, I struggle to find a favourable match up for him.