There’s a Texas tall tale about legendary cowboy Pecos Bill who succumbed to his new bride’s pleas to ride his wild mustang, Widowmaker—a one-man steed previously ridden only by Bill. Of course, the horse bucked her off, sending her flying cloud-high. She plummeted back to earth, landing on her bustle, and its spring-like metal frame bounced her even higher. So there she was, rebounding ever higher, falling ever lower until Bill finally had to shoot her so she wouldn’t starve to death. Sounds a lot like the oil industry, where the front-month crude futures contract plunged to intraday lows just under $40/bbl on the New York Mercantile Exchange in early December from near...