I don’t know about “one helicopter away from greatness,” but there’s no question that he’s a half bubble off plumb.
One brick shy of a full load; Lights are on but sounds like nobody’s home; Locked and loaded but the powder’s wet; Photographic memory but forgot to put in any film; Kink in his slinky.
“One helicopter away from a rescue” And a few fries short of a happy meal.