A captain is a leader and a dictator. His orders are law and his mimic and voice and handling should express power and force and force of respect so it feels natural to obey him. Next to that a captain has no emotion and never ever gives up or breaks character. The crew should give up anything to be in favour of this dictator and if the dictator failes, then the crew lost what tied them together.
It is quit hard to describe this but ill try: My granddad had a captain expression. He had the air of power around him, standing straight up, a very expressed way of speaking... you would not dare to ask him to repeat anything he said, The way he talked and moved forced off obeydiance and respect (Yes he was a warveteran). Cage does not have this. Tom hanks did, barely but he did have it a bit.
Cage is more a politician, he listens, tells all will be alright, asks opinions, agrees with everything, cries, shows emotion, shows a lot of care and does nothing with that information. The other roles he can do is a drunk, psycho or a drug addict. Oh and beeing angry.
So what is the difference:
A captain: I'm sorry your cat is dead. Which #$%^&^%$ IDIOT did not tie that pole. Now clean up this $#*! from my messroom floor. I said NOW!
Cage: I'm so sorry our cat died, yes, yeees, yes it was such a lovely cat -10 minute conversation about how lovely the cat is with crying scenes- How unfortunate that that pole was not tied down. Yes we will find the guy who did it. He needs to be sorry -and when catched- yes we know you are sorry, you must feel horrible and so on.
See what I did there? That is why cage can be a politician and not a leader. People nowadays want a leader that gives them the idea that he cares for you on a pillow. Only in reality that will not make a soldier run forward infront of the wrong end of a gun. Thats why a lot of those leaders fail. The other end? Well easy to make mistakes but lets not go down that road... I think I made my point.