The estimated crowds are boilerplate, of course, but I'm not sure it's realistic to expect 15,000 fans for midweek Nets or Islanders games. Among the concerts, Il Volo is expected to draw 5,500, Def Leppard 10,000, and Janet Jackson 13,500. The circus is expected to draw 5,000.
In other words, the Islanders sure help keep the building busier. Note that starting tonight it looks like they're trying to save money by opening the arena for Nets games only 60 minutes before tipoff.