Milling around the floor-level seating area at the Westville Music Bowl on Friday night, I had no particular idea what I was in for. I had come to review a show by Bleachers, the six-piece band conceived, fronted, conducted, and in every way emceed by Jack Antonoff, the producer and songwriter responsible for approximately 63.4 percent of the songs inflicted on me by Top 40 radio, including large chunks of the catalogues of Taylor Swift, Lana Del Rey, Lorde, Kendrick Lamar, and Carly Rae Jepsen. He is also an alumnus of the band Fun. (period intended), for whom he co-wrote the unbelievably catchy 2012 song“Some Nights.”