This is the first time we're seeing national media scrutinize Pioli (and, to some level, Cassel). And most seem to agree that the resume doesn't look good. So the banner has worked to some level.
If Cassel has a bad performance, I think the floodgate of national scrutiny opens. Of course it will never beat Cowboys or Giants news. But I can't imagine national sports coverage wouldn't talk about it, and maybe even use the video clip.
Great job, PR. This is starting conversation outside of Kansas City that probably wouldn't have been possible if not for the banner. The conversation has changed among national media from "wow, the Chiefs are bad" to "wow... Pioli has been here for 4 years and accomplished nothing."