Understanding timing accuracy
Timing accuracy measures how close each note's actual onset was to where the reference performance expects it, relative to the piece's tempo. 'Rushed' means a note landed early; 'dragged' means it landed late — both are shown per note, not just as one overall percentage.
A small amount of timing variation is normal; Piano's tolerance windows are set generously enough that natural expressive timing doesn't get flagged as an error. What's worth watching for is a pattern — the same passage rushing every time usually means a technical difficulty being papered over by speeding through it, not a deliberate interpretive choice.
The timing chart plots deviation across the whole piece, which makes a recurring trouble spot visible as a repeated dip rather than something you'd only notice by feel after enough repetitions.