Seeing the ball at its contact point. This might be obvious, but it’s not simple. Knowing how to hit a baseball starts with knowing how see the ball.
Because of the different set ups and stances, there are different ways for how to hit a baseball. But once a hitter gets to the contact point that is where all the differences stop and the absolutes and similarities start. If you compare Johnny Damon (who has a very open stance and a leg kick), to Albert Pujols (wide stance and has very little movement), and to David Eckstein (gets in his legs a lot, chokes up and stands very close to the plate) you would find that initially they look completely different.
BUT… when you strip away the pre-pitch rhythm, the leg kicks and all of the other movement that is personal preference, you find that they are a lot alike. The 7 absolutes are seen at contact. No matter how a hitter gets to the contact point of his swing, all great hitters do the same thing.