Using him wrong as in holding up the ball, slowing play down so we don't get countered against?
Or winning free kicks and throw-ins to interrupt any play they have going, and waste time?
Or closing down and putting pressure on the opposition, aiding our very tired midfield?
Or helping the rest of our young players keep their cool, who in the past have a tendency to panic and give away the ball when we're in the lead and it's close to full time?
Good sub, did exactly what was needed. Helped us grind out the win.