Okay, so first of all, let's do a short profile of each of these teams.
Chudley Cannons
The Chudley Cannons were founded by at least 1871, on account of them winning the leagues 21 times and the last time being in 1892. They also tend to lose quite a bit. Club motto? Previous to 1972, it was "we shall conquer." But in 1972, it was changed to "let's all just keep our fingers crossed and hope for the best." Another minor note, their colors are black and orange, and their logo is a double C with a speeding cannon below. See below for an example.
Kansas City Royals
The KC Royals were founded in 1969 (though for the sake of my argument, we'll also include 1955-1967 when the Athletics were in Kansas City). They lose quite a bit; they actually had the worst record in the leagues in 2005 with 106 losses out of 162. There isn't really a club motto (actually, it's your town, your team...as if the entirety of the metro area wants to claim them as their own), but my personal club motto is wishful thinking: let's try not to suck this year. We used to be fantastic, back in the glory days. Team colors are blue and white, and their logo is a KC that's entertwined. There's no crown or anything, but Kauffman stadium has a prominent crown and that particular logo can be seen on the uniforms of the players. See below for an example.
Notice the Crown...
Rookie slugger Billy Butler wonderfully shows off the team's KC much better than I think the crown did. Notice how the letters are connected.
Comparison
Okay. Let's have a look at all of this. Ratio-wise, if we look at the amount of time baseball has been played in Kansas City (and how long the Cannons have played), you will see that the Royals theoretically "went bad" in 1995. Looking at statistics, we haven't had a 500 percentage game since 1994 (2003 is, of course, an outlier in this theory). Which means, that we could in fact say that they "went bad" in 1995. Next. Notice how the KC and the CC look as if they are connected. Very similar. Both teams tend to lose....quite a bit. Colors; black and white are opposites, and on the primary/secondary color scale, blue and orange are opposites as well.
Reality Check
Okay, let's get real. Do I think that JKR meant this intentionally? Not really. Why should she care about baseball, after all. But I do think it's amazing how similar these two teams are. That's my theory and I'm stickin' to it.