Would you encourage a 14U team to do long toss from their knees?
absolutely not, Throwing requires the body to be proper and powerful. This would drill the improper way to throw
Baseball23 You have a PM
If it’s such a bad idea to long toss from your knees then how come Kimbrel swears by that being part of the reason for his velocity?
Many MLB players also say swing down on the ball. Would you do that?
A lot depends on influence of hitting instructor. My kid does indeed have a downward swing and finishes with a “smile”. HS coaches teach same method. Works for him as he’s always finished at or near top of BA, slugging %, RBI’s etc. Don’t think a kid can hear “swing down” on ball & work unless he fully understands & properly taught method. As far as long toss from knees; obviously worked for Kimbrel. Don’t think I’d tell my kid to do it before knowing a little more about it though. By same token; not going to dismiss as wrong.
My answer to such an open-ended question would be “no”. But that’s not because I think there is no value in the drill. Rather, I think drills in general are useless without a well-defined purpose or objective and your question didn’t provide such a context.