There's a lot of "swing up" advice floating around, and some of it is right — a slightly upward path matches a pitch that's traveling downward, so a touch of up is exactly what you want. The trouble starts when a little turns into a lot: the barrel climbs, the back shoulder dives to make room, and now you're sky-swinging under everything, popping balls up or missing beneath them.
The window, not the extreme
The honest target is level-to-slightly-up. A pitch comes in on a downward angle, so a hand path traveling a little uphill meets it flush and drives it on a line. Too flat and you chop over the top of the ball; too steep and you get under it. The window between is generous — but it is a window, and a big uppercut lives past its top edge.
The steep uppercut almost never travels alone. To swing that far up, your back shoulder has to drop and your head has to fall back off the ball — so an uppercut and a collapsing back side usually show up together. That's the pattern to catch, because the fix is the same for both.
What the camera reads
Film open side and CoachVision measures your path into contact — the direction your hands are traveling as you reach the contact frame, in degrees. Positive is a hand path traveling slightly up (the good window); a large positive is the steep uppercut; negative is a downhill chop. The band is deliberately generous on the up side because a matched swing lives there.
Two honesty notes. First, this is a hand read, not a bat read — the camera can't see the barrel, and the barrel sits steeper than the hands. So it's the shape of your hand path, not a measured attack angle. Second, if your head-stillness read is also high, that's the back side collapsing along with the climb — read them together with the frames, not the number alone.
The fix — High-Tee Line Drives
The cure for swinging under the ball is to make yourself hit the top of it. Set a tee at the top of the strike zone and hit hard line drives without popping it up. To do that, you have to keep the barrel flat and drive through the ball toward the pitcher instead of scooping up under it. A steep uppercut simply can't hit a high tee on a line — it'll pop straight up and tell on itself. Ten balls.
The feel is "hit the top half of the ball on a line." Keep your head over it and your back side from dumping under, and the path settles into the window on its own.
Keep it honest
The camera reads your hands and your body, not your bat or your ball — "contact" is your hands' speed peak, and ball flight is something the tracker cannot see. So this measures the shape of your hand path, not whether you launched it at 15 degrees. But the shape is coachable and the window is real: level-to-a-touch-up beats both the chop and the sky-swing. Film one open-side swing, check your path into contact, then ten high-tee line drives a round until "up" means a touch up.