How do I develop my reps into better sellers?

You coach the person, not just the pipeline, and your reps get better because of it. That patience is rare. Most managers grab the wheel when the pressure is on. You keep your hands off long enough for people to grow into sellers who do not need you, and that is the whole point. The quiet risk now is your best reps outgrowing the room you give them. The same coaching that lifted them from good to strong will not take them from strong to great. At some point they need harder problems and more rope, and the loving move is to let them go past where you can follow. Look at your strongest rep and ask what they cannot yet do that the next level requires. Give them one stretch that scares you both a little. Growing sellers means always coaching just past their current edge, even yours.