Possible Clues:

• Inept catcher
• Goat, perhaps, identifies missing person
• A slipping slip?
• Worst one to handle packages
• One who can't catch fire gets burnt in another way
• He can't catch for toffee!
• Careless slip, say
• Hopeless catcher
• Heavy drinkers about to speak to fellow who keeps spilling things
• Hardly the best package handler