I should say no defense will be capable of beating an elite offense consistently. But what you want to do is have just ENOUGH on defense (provided you have a great offense which I believe we do) to match up against what most elite offenses like to do in hopes of slowing them down or in that rare event dominating them.
McDermott knows how to build a defense and Edmunds is a big part of that...will it win consistently against the Chiefs, probably not. But there isn't a defense around that does. We need to be good at what we do (solid understanding of assignments and responsibility, fast laterally from sideline to sideline, quick in run fits etc) defensively and Edmunds fits that.