The year 2017 hasn't been forgiving to the broadcast networks. With a whopping 17 scripted launches since Jan. 1, nearly all new series are languishing with low ratings, even by today's modest standards. But that may not be entirely the new shows' fault: The root of midseason's problem, some say, is the middling fall that preceded it. "In the past, midseason success was typically built on the foundation established in the fall," says Sam Armando, lead investment director at MediaVest-Spark, noting all but NBC (and sports-lifted Fox) are down this year. "Since only This Is Us popped in the fall,...