The fact that I've decided to write this post should surprise nobody who reads Dynamo Theory on a regular basis. Not because I asked for readers' opinions on this subject, but because it deals with something that has been evident to a lot of supporters for a while now. With all due respect to FC Dallas, they do not appear to be the Houston Dynamo's biggest rivals any more. Judging from the quality of teams and matches over recent years, it's fairly evident that the rival label might now be better applied to fellow Eastern Conference powerhouse Sporting Kansas City.

My object here is not to establish an arbitrary rivalry. By the quality and quantity of the replies I've gotten, it obviously already exists, even if its only in the eyes of the fans. I'm simply writing here to offer a glimpse at how and why it might have started.

The dictionary definition of the word rival states that they are "one of two or more striving to reach or obtain something that only one can possess" or "one striving for competitive advantage." There's also an obsolete definition that makes them out to be "companions" or "associates," as well as a third definition that I'll get to later on.

Since the Houston Dynamo moved to Space City in 2006, they've played Sporting Kansas City (in its various incarnations) in nineteen matches that count - fifteen in the regular season and four in the postseason. More often than not, these are closely contested battles - and though both sides can get physical, this rivalry (thankfully) doesn't seem to have a player who seems to always get carded, like Dallas's Jair Benitez does in the Texas Derby.

Speaking of the Texas Derby, people who might not read this site very often are probably asking "But wait, I thought the Dynamo's biggest rival was FC Dallas? What happened to that?" To be as succinct (and tactful) as possible, I'll sum it up in three simple letters: MLS.

In January of 2011, two teams on the west coast joined the league: the Portland Timbers and the Vancouver Whitecaps. As it stood, you had a Western Conference with ten teams and an Eastern Conference with only eight. In order to keep the conferences equal, the easternmost team in the West was realigned to the East. Turns out that Houston was that team, and so after spending their first five years in the West, they switched sides and moved to the East. This left the state of Texas with two teams in separate conferences. While the schedule for 2011 wasn't affected, the addition of the Montreal Impact to the Eastern Conference the next year meant that there would be unbalanced schedules, and that inter-conference fixtures would happen only once - making the contest for El Capitán a single, winner take all duel.

So to shorten the story a bit, at least part of the reason for the decline of the Texas Derby comes from the fact that the two clubs are now in separate conferences. Make no mistake - these two teams still dislike each other, and play can be plenty physical (see Benitez, Jair or Clark, Ricardo). Even with one or both clubs under-performing, the howitzer is still considered a glamorous prize - at least inside the state of Texas.

But a preconceived rivalry (and make no mistake, that's exactly what this is) is one thing. Local rivalries are common, generally building off of regional pride - look at the Subway Series (Mets-Yankees) in baseball, or Flyers-Penguins in hockey, to name a couple off the top of my head. These are good, logical rivalries, but many of them start to seem as if they're pushed more by the media than by anything else. If both teams are good, then it's not so bad. But when one (or both) teams are bad - when it always seems like the rivalry has a single, predictable outcome - it loses much of what makes it worth watching.

Enter the other type of rivalry: the one that comes not as much from geographic proximity than it does from proximity of potential skill. This can include local rivalries, of course - look at the NFC and AFC North divisions in the NFL, for example, or Ohio State-Michigan or Texas-Oklahoma. For these, it's not just proximity on a map that makes them rivals. In the cases of the two college rivalries, they also fight over many of the same recruits. I can also guarantee you that the Pittsburgh Steelers take a game against Cincinnati much more seriously than they do one against Philadelphia. In cases like this, the division play has enhanced a strong local rivalry.

But what if the two teams aren't close to each other? Why are teams like the Eagles and Cowboys such bitter rivals (note: there's a very good reason I didn't use the Redskins in this, but that's for another day)? Because so often, they find themselves on opposite sides of a field with a division title on the line - both teams striving for an accolade that only one of them can obtain. Same thing with the Braves and Astros - two teams from separate divisions that found themselves facing each other what seemed like every other year between about 1994 and 2005 in the playoffs. In cases like these, a prolonged string of strong play from both teams elevated the match-up from mundane to a rivalry.

When I posed my question of when and why the Dynamo-SKC rivalry started, the above reason seemed to play a part in the most common answer. The two teams had played each other fairly well before realignment, but when league expansion brought the two into the same conference, they suddenly found themselves in each others' way. Through a quirk in the playoff format, they had met in the conference finals once before, when the Dynamo won 2-0 at Robertson Stadium en route to their second straight title in 2007. Now, however, there was the potential for the teams to meet in the playoffs every single year.

The first two years proved exactly that: in 2011, the teams met at Livestrong Sporting Park in Kansas City for the Eastern Conference final, won 2-0 by Houston, and they met again in a first round playoff tie last season. In the tie, Houston won 2-0 at home, then held off a Kansas City rally to take the tie 2-1 on aggregate. While Houston has won more matches in the all time series, in my opinion it's been a lot closer than the Dynamo's 9-4-6 record would indicate. The only matches I would describe as a rout were the Dynamo's 3-0 home victory on 1 May 2010 and Kansas City returning the favor at their place on 10 September 2011. Thirteen of the nineteen matches have either been draws or one goal victories (not included is the 2012 playoff tie, which ended as a one goal victory on aggregate).

While the majority of responses indicated that most people believe that the rivalry came to the forefront because of the 2011 Eastern Conference Final, there were a few other answers that caught my eye. SKC supporter Eric Hunt (@OliverKahn987) thinks it goes back much further, to the days when Kansas City still played at Arrowhead Stadium (note: you can check me on this, but I believe the two teams only played two matches there, in '06 and '07). Both he and The Daily Wiz blogger Mike McGrew (@CincySporting) note that to Kansas City supporters, one of the major frustration factors is the coaching style of Dominic Kinnear, and how he always seems able to neutralize KC's tactics.

A conversation between Darren Reed (@TheNumber65), Matt Terrill (@Matt_Terrill) and I touched on Kinnear's coaching, the physicality of play (something which many supporters agree that both teams are known for), and what seems to be two completely different attacking philosophies - a team that relies a lot on set pieces versus one that gets most of its opportunities off the run of play.

There were also some differing opinions on from Dynamo supporters. Our own staff even offers other opinions on how the rivalry seemed to come about, mainly relating to various players involved. While Fusion seems to place at least some of the blame on the antics of Aurelien Collin, Ordinary Orange Fan is of the opinion that it stems from Kei Kamara, who has played for both teams. Kamara was traded from Houston to Kansas City on 15 September 2009, and every time he would face the Dynamo, he seemed to play with a little extra intensity.

Devin Brown (@TexasDevin) suggests that it stems from FC Dallas not "living up" to their side of the rivalry, and the date he gives is 5 May 10, the last time that FCD won in Houston. Likewise, a Real Salt Lake supporter, Denzel Eslinger (@f4denz), added his opinion that it began when MLS schedules started to neglect the Dynamo's existing rivalries with Dallas and San Jose (he added RSL to the list as well). I think both of these were fueled (at least in part) by the realignment of MLS two years ago - if you're going to define a rivalry as a match-up that happens often, then you can't consider any Western Conference team a true rival, as the Dynamo only play these teams once every season (not counting any possible MLS Cup match-ups.

While that might fly to some supporters, it doesn't to me. Those rivalries are already established, and while their luster may fade (which it undoubtedly has, otherwise I might not have any basis for this post), it never goes away completely. The proximity of Houston and Dallas means that any match between these two teams will always have a little added flair. The same can be said with any match the Dynamo play against San Jose, since the history of the two clubs has forever linked them together.

That being said, I don't believe that either rivalry comes close to that of Houston-Kansas City - at least, not at this point in time. While this is a debatable point, most supporters of both teams can probably agree that these are two of the best three or four clubs in the Eastern Conference (and probably in the top five or six in all of MLS), which brings me to that third definition that I mentioned. In a true rivalry, the two rivals will be equals or peers. Let's face it - the most intriguing match-ups to watch are usually those by teams close in ability to each other. Yankees-Red Sox, Lakers-Celtics, and Real Madrid-Barcelona are three prime examples from different sports. More often than not, these are teams in the upper echelons of their respective leagues, with talent and ability that are nearly equal to one another.

Is this a rivalry that's at that level? Probably not, but I doubt that matters to anyone who likes either of these teams. It might not be the best match-up the world can provide, but it is one that supporters in both Houston and Kansas City circle on their calendars. It may not have always been like this, and it might not be one of MLS's "official" rivalries, but I'm not sure there's many match-ups in the league that I'd rather watch - which is generally another sign of a rivalry.

Also, before I turn this over to the peanut gallery, I'd like to take a bit of space to thank everyone who answered the query that led to this post. Andy Edwards (@AndyEdSKC), the editor of SB Nation's The Daily Wiz, was a big help in getting my question out to Kansas City supporters. I realize that I didn't mention everybody who got back to me, and I do apologize for that, but I could only touch on so much before this became overly long. If you want to see more opinions, they can be found in the replies to tweets by Andy and the official Dynamo Theory account. I'm sure they'd all appreciate the followers, and I always find it good to extend your acquaintances beyond people who support the same teams as you do. Friendships can survive differences of support, and if nothing else, it's always something y'all can debate amongst yourselves. You can start in the comment section below - feel free to add your two cents to my ideas.