Because basketball is a game of separation, defense denies or delays separation. Offenses can create screens in numerous ways, catching defenses in traffic. Well-set screens with cuts 'set up' and urgent cutting are hard to defend. Tight defense invites screening and back door cutting.
Never think it's easy. See this 7 second nightmare for the defense from Basketball Immersion (above).
Here's the full video from Chris Oliver's site, an argument for screening.
Offenses establish off-ball screens in a myriad of styles.
Core concepts: (introductory)
- There is no "one way" to do things.
- Communication is essential. "Silent teams lose."
- Whatever "your way" is, get everyone on the same page
- Ball pressure matters. Don't make entry passes easy.
- Help from the screener defender is also key.
- "The ball scores." Off-ball defenders must be aware of the ball to give help when the ballhandler gets penetration.
- Some teams switch everything, some switch "big on big" but offenses can create small on big situations to create mismatches
- On the "help" side, we can switch, go through, or "jam" and go under.
On the low cross-screen, it's important for defenders to be on the high side to avoid the seal and post entry. With small screens on big, fighting through the screen is critical with x5 starting "high". It's not a given that 1 has the bulk to screen x5. If the situation is reversed and 5 is screening x1, x5 has to loosen coverage enough to get x1 through and be able to recover to 5 with hands high.
When defenders are in "ball-you-man" position but NOT loading to the ball, they allow better screening angles and more space for offenses to operate. Good offenses "win in space" and good defenses "shrink space" and get offenses to play in traffic.
Generally speaking, officials "allow" more physical play without the ball closer to the basket. That doesn't invite "dirty" play, but contact to divert crossers is essential.
Coverage also depends on the skills of the players involved. x1 may try to body the screener and allow x4 to go under the screen, especially if x4 is less of a shooter. Or x1 can drop, allowing x4 to go "through" the space. It's a matter of coaching preference.
Terminology is an issue. Some teams prefer the term "lock and trail" for some "catch up" screen coverage, especially on the ball side.
Remember the maxim, "great defense is multiple efforts" because offenses are so good. Only extraordinary effort can slow them down.
Understanding what offenses are trying to do (below) helps us understand why they can be almost impossible to stop at extreme NBA skill levels.
It's so difficult to stop good execution that it's always a work in progress.
Lagniappe (something extra). Develop the floater game. This video shares helpful individual improvement tips.