[jcranmer]

What was pointed out was that the way the Greeks organized their battle formations, the strongest of their formation would generally face the weakest of their opponents' formation. Since Spartans were usually seen as the strongest, this meant they faced generally those seen as the weakest. And he also points out that when this general model is explicitly broken, the Spartans really suffer in their documented military effectiveness.

[klipt]

That's pretty interesting. So it was basically confirmation bias: people thought they were strong, so they were put in positions where they performed well, which perpetuated the idea that they were strong?