My eldest son had terrible mechanics as a shortstop and second baseman. Really - just horrible.
Incredibly - in his senior year in high school - his coach brought him in to pitch on a 35 degree day. Never pitched in high school before. He threw about 5 pitches - and I just winced.
He was never the same after that day - and played with a bad arm for the next 3 years.
Thankfully - he had TJ surgery after his 3rd year in pro ball - changed how he threw the ball - and plays painfree. Believe it or not - he actually has a pretty good arm as well.
The damage done - by bad mechanics - and moronic coaches - will eventually catch up with you.