The majority of players don't understand the importance of timing nor how to fix it. You can have the best swing in the world but if you are not on time it does not matter.
Recently we were working with a player who keep getting frustrated at his performance. While observing, I noticed him go through his mechanical checklist making sure his movement pattern was correct. "Your mechanic are not the problem your timing is. Try this. As the pitcher releases the ball yell out Riiiiiiiiiight and Now at contact."
Within three pitches his timing was perfect and he began hitting the ball hard again. In order to perform you must first understand.
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