A fair-weather fan is defined by Urban Dictionary as "a fan who only likes a team when it is winning." For this reason the Kansas City Royals will not be on this list since their fans don't seem to like them at any time.
A great example of a fair-weather fan would be the "New Dats." Who dat, you ask? The "New Dats" are the brand new New Orleans Saints fans who crawled out of the woodwork when the Saints opened up a can of whoop ass on the 2009 NFL season, winning Super Bowl XLIV. Where were these fans when the Saints were bottom-dwellers for so many years?
Now that that's out of the way, here is the list of the most fair-weather fans in all of Major League Baseball. In order to attempt to save myself from extreme ridicule in the comments section, I have based the top five teams (in no particular order) with the most fair-weather fans on a mathematical formula. I found this formula on mkaz.com, which provided charts plotting attendance versus wins for each individual team over the past 20 years.
With these graphs you can tell if the average annual attendance for a particular team went up or down based on the number of wins per season. Hence, you can determine if a fanbase is fair-weather or not.
Though the top five fair-weather teams were determined by plotting and completely prevent you from blaming me for the outcome, I definitely don't want to take away all of your fun. For this reason, I most certainly plan on throwing my two cents into the mix to let you know if I feel the ranking to be justified.
In addition, the graphical information only takes into account attendance at the ballpark. Fans exist everywhere and cheer their respective clubs on from their living rooms, bars, etc....I will take this into consideration in my analysis.
Also just for fun, I'll throw in a couple of the best fans and worst fans in baseball, according to the data. Thanks for reading and commenting. Enjoy.