I write runs and wickets in terms of points. The run average for a Test match is the total runs scored divided by the total wickets fallen. 10 runs make 1 point, therefore 1 wicket is the run average divided by 10. A test match is said to progress with the fall of each wicket. The total points scored by each team is calculated at the fall of each wicket. This is essentially the state of the test match at that point in the test match.
The graphs reveal the extent of Australian dominance at Brisbane. They also reveal that England were in a similarly strong position early in the Australian first innings at Adelaide.
Several important conclusions can be drawn from graphs like these. Conclusions about competitiveness, conclusions about the story of the match. All the twists and turns become apparent. Below is a graph of a closely contest test match consisting of 4 completed innings, the lowest of which was 238 and the highest 286. The final result was a 12 run win for Pakistan.
Competitiveness can be visually assessed by determining the number of times the lines of each team cross. Surges, partnerships, batting collapses, trends etc. can also be visually assessed. In the Chennai Match, the two surges are Afridi's century and Tendulkar's century, both of which threatened to break the deadlock, before the spectacular collapse at the end (revealed in the graph as well), sealed Indias fate. All in all, this seems to be a robust method, which i have used in my ratings as well as here.