From Ron Sen Basketball (se link for more)
"For youth coaches, expecting consistency will only cause frustration. Learn to deliver teachable moments.
Basketball isn't like some other sports which allow for specialization as a defender (e.g. baseball defensive replacement) or offensive player (designated hitter).
Errors occur in stance, position, execution, and more.
Let's review a few and suggest corrections.
1) Stance
Players need footwork, balance, and maneuvering speed. Many high school players play too 'upright', limiting footwork and balance. "It's a shoulders game. The low man wins." Ultimately, players must learn to defend "live" although here's a Coach K drill. "