I don't know this agency so I can't speak on their behalf or understand what they're doing exactly. But it needs to be looked at beyond just CPC or even CPA. My approach is that I target the right audience that will be more profitable to you, even if that means higher CPC/CPA, but I make it up from less-profitable targets. If that's what they're doing, then it should be no problem. And it's difficult to get this done right off the bat so give them time. But you should understand clearly what their strategy is so I would ask if you're not yet sure.