Firstly, will people PLEASE leave superman out of this...
yes, he has the will to win, but he also has the powers in most cases to back it up... and the fact that he pretty much never uses his full abilities to the full...
another thing... i saw someone say that logic doesn't apply in comics... which is wrong, logic does apply, its just that writers sometimes tend to ignore it, physics, as we know them, and the general boundaries of science don't...
cap lasting against iron man is PIS, why? tony is stronger (f*ckin hell, he's herculean compared to cap), just as fast (edit: faster), and his suit gives him insane durability... given cap's abilities, logically (see, there it is) he should have no chance against Iron man... yet he does,and why? PIS...
because simply put... no matter how angry or willful you are, ability still plays a huge part in winning or losing a fight...
if absorbing man is within arms reach of cap, then cap should end up decorating the nearest wall with his own brain...
its only smarts in very small cases, most of the time its just plain Plot Induced Stupidity...
in short, PIS in a lot of cases = absence of logic...