Astute observation.  I believe in one of my Viola Spolin books, where she records a "class", often her students do not perform an exercise to her liking.  She tells them she did not believe in what they were doing.  They often replied (in explaining their motivation), "Well, I was thinking about how my father left my mother when I was young." And her reply was always something like "And how are we the audience supposed to know that???"

I like this idea, and it's not original: imagine standing on a sidewalk watching two people through a store-front window.  You can't hear them, their words, their vocal tone - all you get is the visual of what they do.  From that, you can often determine what's happening between them. The body language, gestures, eye-rolling, glancing about, etc. 

In a workshop, I'll give an actor an instruction such as "be angry", or "be bored".  We know that those are emotions, and as such are not actable in their purest existence.  So how do you act angry or bored? By your actions.  You "do" things that an audience will associate with the emotional context, whether it's movement or postion or vocal delivery.  And when you, as an actor, do that, are you really angry or bored?  Of course not.  It's about what you do, that is what the audience receives.

The internal life an actor imbues a character with is helpful only to him or her in the presentation of that character to the audience.  They will never know of the character's father always missed her birthday party, or the mother never went to a school recital.  It's how you the actor use that to create the adult character on stage that avoids rejection and commitment and love.

An audience may not understand your words, or maybe they mishear them, or don't hear them.  But they see you.  The visual is always "on".  There are no closeups on stage.  If you're onstage, you're "in the shot", even when you have no lines.  Be worth watching.