The level plot keeps the original values: 4, 7, 5, 9.
The change bars answer a different question. They show the size of each move after the first point: 3 from t1 to t2, 2 from t2 to t3, and 4 from t3 to t4.
A tiny EDA view: plot the same pinned time-series levels as dots, then plot absolute period-to-period changes as bars.
highlighted = computed this step
Pinned levels and changes
Start with exact levels, then compute each period-to-period change magnitude.
levels and changes
Level dots
Dot marks show the level at each time label.
level dots
Change magnitude bars
Bar marks show how large each step-to-step change is.