It’s not real functional training especially only with 20 kg. It’s good warm-up exercise that makes work all muscle groups. In the same time you need to have good shoulder mobility and good technique.
The use of barbell is to make instability on shoulder. Of course with kettlebell around 30/40 kg the exercise will be really good work for strength and dynamic. First step for your players…. Learn the exercises in right technique and after put all together.