I agree that Heinola hasn't shown enough to be granted that 3rd pair role.
My point is that the Jets need a better D than Stanley in that role if they want to be a real contender, and I have tried to support my opinion with specific examples (like mistakes or penalties at key moments). Of course other D make mistakes too, but I don't really see the benefit with Stanley, especially in the playoffs when the pace increases substantially and fighting becomes even less relevant.