Re: Let The Hero Lose.
Iron Man should lose one since going gung-ho against the grain when he believes he is right and then later having a "Oh, maybe I really shouldn't have done that" moment is so in line with what his character has always been about....being human and making mistakes(sometimes really big ones). Just incorporate that into a villain winning against him for once.
You know, it occurs to me that Captain America is basically the superhero equivalent of Mary Poppins. Practically perfect in every way and all that stuff.