The Pittsburgh Penguins, after battling its way to the Stanley Cup finals with a double-overtime Game 7 victory, started the 2017 championships handily, beating the Nashville Predators in the first two games. Then the Predators countered with a pair of scrappy wins of its own. Tonight is Game 5, and this year’s Stanley Cup is now, in effect, a best-of-3, winner-take-all series.