i think that a big reason coach Cavalea is against it is that a lot of the programs hes seen seem like they arent good ones. If all a program does is throw weighted baseballs as hard as possible, yeah theres a good chance of injury. I think a lot of people see Kyle's stuff and assume all they do is chuck weighted baseballs super hard. They also do a VERY thorough warmup, plyocare work to optimize mechanics, recovery protocol after throwing every day, and lots of weight lifting. It certainly is more than just weighted balls. If any of you own HTKC, you'll know in the sample programs that the first month you dont touch a weighed baseball. Not sure, but it seems like a big part of Dana's reason for not liking them is that the programs hes seen haven't been good ones.
As an aside, I've seen Aroldis Chapman throw a heavy baseball.