Stewart’s marking is definitely improving. Not saying he’s yet nor probably will ever be as good in that regard as Hooker, but if he can just do enough as the second KF to keep a defender honest, the same qualities that make Hooker such a great forward have desperately been missed in the backline since his departure from there.
As Killer Mike said, it’s about getting the right balance, and it’s a tough decision for the coaches to make; wherever they put Hooker, forward or back, that line will be much better than if he wasn’t there.
Much of the decision probably rests on the midfield. If they’re conceding 50s entries more than they’re producing them, then the Hooker boost would probably be best given to the backline, and vice versa.