How to compare two baseball swings without fooling yourself.
Side-by-side video can make progress visible, but only when the clips are comparable. Camera changes can create apparent mechanics changes that never happened.
Match the camera angle first
Use the same view, approximate height, distance, and aim. If one clip is side-on and the other diagonal, limit the comparison to observations that remain valid.
Match the intent and environment
Compare similar drills, pitch sources, effort levels, bats, and constraints. A tee swing and a high-velocity live at-bat answer different questions.
Align the same phase
Compare load to load, heel plant to heel plant, contact to contact, or finish to finish. Aligning by elapsed time alone can hide tempo differences.
Choose one checkpoint
Head position, posture, stride direction, contact depth, or finish balance can be useful. Avoid turning one comparison into a full swing diagnosis.
Write down what actually changed
Save a note describing the drill or cue and the visible result. That context is what turns two clips into a useful training record.
Keep the better evidence, not only the better outcome
A hard-hit ball does not prove every movement was better, and a poor outcome does not erase a useful mechanics change. Review the movement and result as related but separate evidence.