KC defense is "bad" in that it doesn't have lockdown players in the secondary. But the scheme is very solid there, and worked effectively last Sunday. Pressuring Lamar and giving him very difficult reads, so even if his receivers were sometimes able to get open he wouldn't have an easy throw. Also helped that Andrews wasn't playing to his usual level (he looks hurt).
Plus having Chris Jones and Frank Clark up front has really helped them cover up some holes that were exposed last season.