NBA defenses are in their own version of the dark ages. Offenses are averaging an eye-popping 111.5 points per game, and the league’s rule changes are making things even more difficult for defenders.

The pace-and-space style of play is completely changing the way teams defend, so most coaches are using switch-heavy defenses to counter the small-ball lineups that are becoming so prevalent around the league.

“Here’s the problem: Most of these guys don’t really know how to play a switching defense,” one NBA assistant coach who specializes in defense told Brian Windhorst of ESPN. “They weren’t raised playing this way. It sounds simple, just switch everything, but actually it’s hard, and not that many guys do it well. Not that many units do it well.”

Switching all screens isn’t generally something that happens much in AAU or high school games. Teams will do it in late-game situations when they really want to run teams off the 3-point line, but it’s not nearly as prevalent a style of defense as it is in the NBA. Teams don’t shoot like the Golden State Warriors, so teams don’t need to switch everything as a counter.

That’s why some players have trouble adapting to this style of defense in the league. It’s not something they’ve had to do much throughout their careers, and it doesn’t always work right off the jump.

Teams will continue to try to adapt and scheme their way out of this offensive eruption in the NBA.