These are not random fighters, these are githyanki. It's totally logical that they would be crazy strong. Consider that Lae'zel at the start of the game is a rookie trainee who hasn't accomplished her rite of passage into adulthood yet (you do that by bringing back a mind flayer's head). These, by comparison, are supposed to be seasoned warriors. Even experienced adventurers who are familiar with their kind would be tempted to turn and run.
Seasoned warrior means higher experience level, not absurdly high ability scores that break consistency.
