The real act of creative genius here resides in Jimmy Fallon’s recognition that somewhere inside “Pants on the Ground,” Larry Platt’s unimaginative, one-dimensional, condemnatory lyric, there lurked the potential of a classic Neil Young lament for one’s own youthful lack of self-awareness: introspective, elegiac, self-mocking. If you hadn’t heard Platt’s version, or learned of the hoopla surrounding it, and this came over the radio without you knowing it was Fallon’s, you’d think it was middle-period Neil Young himself. […]