Adam, your point first...
they lost. They failed their test and got a RETREAT result. This is not as unlikely as you make it it sound. A ROUT would simulate mass panic and a collective desire to run away and save your life.
RETREAT represents the collective psyche state which is not quite as bad as that..
the men have fought and lost, they don't want to fight anymore and they don't want to listen to their officers either. They cannot act collectively in their own defence anymore and have decided they've had enough and they want to move away from the danger. It may start with a trickle of a few faint hearts which erodes cohesion enough to make the unit no longer combat viable. More men join in, they may be fighting back locally but NOT TO WIN only to get away.. hence no casualty inflicting options for the retreaters.
Jim, your point..
The infantry would have taken a -1 for chargers behind flank in their test to stand.. if they still stood.. Good Boys.
If the cavalry failed to do a single casualty with 6 dice at odds of 50% then I can't help that! The infantry in this case did well. It's not all Charge of the Light Brigade
.. but Jim you've been hanging around wargames tables since Moses left Partick so I think you knew that already
Often guys the results that we have most trouble with are the ones we thought were going to be battle winning or saving moves that don't work that way..
If you don't like the answers then blame ME.. I can take it