We have a great hitting Juco team that doesn't use a cage/machine. They go from hitting off a tee into a mat, to front (behind screen) toss at 10ft (simulates a fastball), to live BP from 46ft. All of them have a MLB swing. I personally don't know any coaches who teaches hitting ground balls. On our season so far, only 2 or 3 hits have been from ground balls. Everything else are line drives to the gaps and bloopers over the IF.