Be very careful with the weighted ball. My son, after years of hard work at academy level blew his shoulder out, effectively finishing his ambition to play pro cricket.
I agree with this point I practice with 3kg ball and trust me I spend 15 minutes warm up for my shoulder also I only throw with my bowling action standing not giving too much stress to shoulders and I hope your son have a quick recovery and comes back in cricket I know the pain of not playing cricket because I have asthma I'm making slow comeback let's see ❤