Offense is back in the N.B.A. Look no further than the triple-digit scores now appearing nightly. And defense? After slowing the game in the ’90s, it has lost a step. And yet defense is still critical to a title: 34 of the N.B.A.’s 61 champions led the league in scoring differential, a defining defensive measurement. By contrast, just 10 champs have topped the charts in scoring. Here, former head coach Jeff Van Gundy, outlines ways to stop some of the game’s most potent offensive weapons.