Size and athleticism help but don't replace technique. Proper defensive positioning emerged as an issue for us today. It won't happen automatically or overnight. But it's on me to help our team understand and execute.
Alertness and awareness inform defensive reaction and execution. Players have to "see both" the ball and defensive assignment. As a middle schooler, we faced a grim reminder of losing vision...a volleyball would come flying out of nowhere at us. We learned... although this would never be acceptable today.
"The ball scores." x4 helps but other help defenders, like x3 must "help the helper" to protect the basket. Communication with help and recover actions are at the core of team defense.
Even if a young team spaces well, 4 and 2 won't hurt you consistently with perimeter scoring. Get into position to help and then recover to your assignment.