If it’s live pitching then your problem is probably just timing a pitcher properly. Different pitchers throw at different speeds at different times whereas a machine throws essentially the same pitch over and over.
Make sure your stride foot hits the ground before the ball is released but not so early that you get thrown off balance. Pay attention to the pitcher’s motion, time your stride according to the tempo of his delivery, and remember some pitchers you will have to wait as long as you can and some guys you will have to consciously try to hit it a little further out in front of you. But don’t get caught up in only hitting his fastball remember to keep your eye peeled at recognizing an off speed pitch.
Hammer described pitch recognition very well in another thread I think just one or two threads below this one.