Whats worse throwing a curveball every 8-10 pitches with good mechanics or throwing a fastball with poor mechanics?
Mechanics are more important, and studies have shown the a FB puts more stress on the elbow than a curve. To me, what’s more important that the kids keeps their arm in throwing condition and works to keep the muscles, tendons, and ligaments strong. That means doing doing a Thrower’s Ten type of regimen, and throw! That doesn’t mean year-round pitching. It means to throw some year-round with some periods of lighter loads to allow some recovery, and keeping an eye on innings where the kid struggles. If a kid can’t keep an inning to 20-25 innings, they need to sit and wait for another day.
Think the more relevant question is does he have command of fastball & changeup? I don’t believe throwing a curveball at age 12 in and of itself causes more stress than a fastball. I do believe however development of intent (to throw hard) is more important than developing a breaking pitch. Kids have a tendency to fall in love with a curve due to sucess at a young age. Would also prefer mine learn a changeup prior to a breaking pitch. A curveball is easier to learn than a change, many kids get to HS & don’t have one.
My son is 12YO. We’ve only just started with the CB since last fall. He still throws FB/CU with a few CB’s thrown in during the game. At 12YO the CB is a deadly pitch against most batters. But as the kids get older, the CU becomes more important.