If you have either listened to Coach Nick at BBall Breakdown or follow him on Twitter @bballsource, you've seen him rant on teams and players who are prone to bad tendencies in defensive help strategy. The video above explains it perfectly, along with real demonstrations to help you see what he's talking about.
The trouble with the bad practice of one pass away help defense is that smart offensive teams like the Spurs and Heat will prey on defenses who make this kind of mistake, and the result is a plethora of wide open corner-3's, statistically one of the best shots you can take in the NBA. As Coach Nick explains, he drills this into his players so that their muscle memory is greater than their reactionary tendency. If a player sees his teammate is beaten off the dribble, it is a natural tendency to help. However, as we know guys like Tony Parker love to do, the drive is there to set up the 3-point shooter who is an easy pass away. Furthermore, as teams get into the playoffs and fatigue starts to set in, bad defensive habits become a greater and greater tendency, and that's where breakdowns occur.
The Thunder perform reasonably well in avoiding this tendency, as they are a top 10 defense. However, in giving up nearly 22 3-point attempts per game, they still have a tendency to allow their overaggressive athleticism to replace solid defensive rotation. As the Thunder continue to grow in this area and utilize the fact that they have the best shot blocker in the game in Serge Ibaka protecting the rim, they will see these open 3-point attempts drop and their overall defensive performance go up. Given that OKC averaged nearly double digits in point differential a year ago, this is a promising prospect for the team and a scary one for everybody else.