Running efficiency explained in one image

This photo beautifully captures the concept of running efficiency in a single image. Take a look at the tall chap in red and then at the shorter lad in a white T and black shorts to his immediate left. Who do you imagine is working harder? Who would you guess finished higher? The answers are intuitive, but why is that? You know who won but can you explain it? If you can then you are on your way to being able to build speed.
The fastest athlete has the greatest differential between available energy (strength/ work capacity) and 'cost' - the energy the body spends to produce a given level of power output. The problem for Mr White T isn't his power output (strength) - he's essentially even with Mr Red T. His issue is that his power output is costing him considerably more - he's bleeding energy whereas Mr Red T is cruising. Game over.