he talks what talk? he walks what walk?

I think you need context for that. Say that the guy in question is some politician claiming to be able to fix healthcare in Canada. Then you ask yourself, "He talks the talk [of someone who can fix healthcare, he claims he can actually do something, makes it sound like he knows what he's talking about] but can he walk the walk [can he actually do it or is it all hot air, all just talk?]"

Or, with a non-negative example, you're watching a guy speak about child poverty and you know that he's been involved for 20 years in community-based organizations to help poor children. Then you say to your skeptical colleague: "He talks the talk [about fixing child poverty] and walks the walk [he has actually worked toward doing so]."