Then make sure Jim knows and feels your appreciation. Maybe Jim doesn't want the attention or questions (or at least doesn't value the prestige/benefits at the cost of the attention it requires). Many times the person who will churn out work in a dark, unappreciated corner will continue to do so if 1 person who they respect shows them enough respect in kind. They know the world they're in. No one expects plumbers to get a free lunch even while many know they should.