He is not 'capable of' making those medical decisions himself. [=he cannot make the decisions by himself because he cannot think clearly, he is too sick, etc.]
I don't believe that she's 'capable of' murder. [=that she is the kind of person who could murder someone]
She is one of the most 'capable' [='skilled'] and versatile actresses in Hollywood.
(..) Just warming up, coach. Got a little inside info for you. The scout from Ohio State is back, and the coach is with him. You play half the game I know you're capable of... ...you're going to be playing college ball next year, huh? - That's the plan, coach. - Give me the ball. (..)2009 17 Again
(..) O'Donnell, save something for the game. I'm just warming up, coach. Just talked to the scout again. He's coming tonight. You play half the game I know you're capable of... ...he's prepared to offer you a full scholarship. Free ride to college and the world's your oyster, kid. Thanks, coach. (..)2009 17 Again