I see the chart as an attempt to demonstrate that one’s point of view has a direct impact on how one sees progress. Using the 80,000’ strategic, soaring eagle’s view of the world, progress towards one’s goal(s) may seem to be linear, as the straight line shows. However, one needs to remember that the stopwatch needs to be rewound or it will slow down and not perform as desired—hence the downward slope of the line. Another interesting point about the eagle’s eye view is that as the eagle dives towards its prey, it loses the ability to see other options. It may end up with a meal that is sub-optimal. By focussing on the chipmunk during its dive, it may miss the javelina 100 feet away.

At the ground-level, tactical, worm’s-eye-view level, one starts with a monolithic effort, or coherent/cohesive force, as indicated by the original Jenga tower. The wavy line seems meant to show that progress at this level is much hard to track. Over time, the tower loses its structural stability as blocks are removed. Removing blocks may represent fragmentation of effort away from the original single focus. It may also represent a fracturing of the original force structure caused by asymmetrical unit rotations or an overall reduction in the deployed force. Others have already noted another aspect of the unpredictability of stability caused by the Jenga blocks’ removal: uncertainty is introduced as each side makes its choice of a next play. That is part of the reason that stability of the tactical effort is rather unpredictable.
As an aside, to those who haven’t played Jenga, sometimes removing an additional piece brings a little more stability to the surviving structure. Of course it is not as stable as the original monolith, but it may be more stable than a preceding combination.

One thing I do not like about either metaphor is the pessimism that seems operative in each, reflected by the downward trend in each line. Another problem for me was much better put by Tom Odom’s metaphor. I can put this slide to a lot of different uses, not least of which is a mystical example to obfuscate what I took to be an obvious point. (Slapout MTV’s “All Along the Watchtower” link works here: “There's too much confusion, I can't get no relief.”) Maybe Slapout MTV also needs a link to the Stone’s tune, “You can’t always get what you want.”