In fact, the best way to avoid something like this is to say that you never let them lift a weight in which they can perform less than 10 repetitions. If they cannot, you back them down to safer weights and increase repetitions. By increasing reps, the young player is forced to lift less weight which consequently is safer for the developing skeleton. Speed of movement of the lift is also something to control. All lifting movements for this age should be at a controlled speed.
Explosive lifts are hazardous and can cause damage to the musculoskeletal system.
As one weight lifting expert offered, it may not cause an immediate problem but explosive lifting will certainly position a young athlete to future injury. Another critical element of strength training and athletic development is range of motion . For adolescents all lifts should be through the great range of motion possible. This will increase their flexibility and reduce their chance of injury doing partial range of motion lifts. Finally Coach, you are about on target in terms of the length of a productive daily program.