Surely the NFL, that famed league of parity, has extremely varied teams who are successful each year! Actually not so much. Looking at the past 10 years we have merely 7 different Superbowl winners, as the Patriots and Steelers have won multiple games. The Colts and Ravens have also won, thus narrowing the "Surprise team" victories down to just 3. Aside from Superbowl victories you can count on several teams to succeed every year and several teams to suck every year. Quoting this article:
"The fact of the matter in today’s NFL is that four teams — all in the AFC — have held an iron grip over the NFL for more than a decade. Denver, Indy, New England and Pittsburgh can be counted on year after year — with the occasional exception here and there — to stand among the very best teams in the league. Those four have won 11 of the past 14 AFC titles. They’ve won six of the past eight Super Bowls and eight of the past 12. Over the past 15 years, the AFC’s Big Four have filled 19 of 30 spots in the AFC title game."
The Broncos of course have faded a fair amount since then but the other 3 teams are virtually always good, so are the Ravens, Eagles, Cowboys (down year this year to the amusement of all), and Chargers. I'm not sure what inspired the NFL to promote itself for parity but every year we see the same teams succeeding and the same teams failing. The Lions, Panthers, Cardinals, Texans, Bills, Bengals, Browns, 49ers, and Redskins are almost always bad. The Bengals had a few good years between decades of sucking, whoop de doo. So, seeing that parity is a myth one hopes and dreams that announcers will stop blabbing about it and how important the salary cap is in creating it.
Well, the NBA is slightly different in that it wants good teams to succeed to promote itself. Generally speaking no one watches the regular season of the NBA, not even people from the cities where the teams are (though I've watched about 4-5 Heat games this year out of curiosity), so for that month and a half of playoffs they need a lot of press behind specific players and teams to generate attention (i.e. Lakers Celtics or Lebron vs Kobe). However the NBA still does have a salary cap in place.
Looking at the past 10 years the Lakers and Spurs have won 7 of the past 10 championships (and 9 of the past 12), with only the Heat and Pistons being genuine surprise teams as the loaded big three Celtics won it a couple of years ago. Just looking at the West only the Dallas Mavericks have managed to even get to the finals in 1 year out of the past 12, every other year belonging to the Lakers and Spurs. Once again as with the NFL there are consistently good teams and consistently bad teams, but the NBA is perhaps the worst offender of the major sports in this regard, as the playoff teams are almost the same every year, and certainly the successful teams in the playoffs are. Looking at the current standings there are 3 teams around .500 and 14 teams that are in excellent shape for the playoffs and the rest are in horrible shape. We're barely 1/3rd of the way through the regular season and half the teams looked to be mostly eliminated.
*Gasp* the league of reverse parity where the Yankees and Red Sox buy the World Series every year! Looking at the past 10 years there have been 9 different champions in the MLB. 9/10! Not only that you could classify 5-6 of those teams as surprising victors. The Red Sox and Yankees are great teams every year but that is almost it in the entire league, several other teams are consistently good but not consistently great and there is no real dynasty team out there. The MLB has no salary cap or limitations on spending, so why then is it the fairest league in recent years?
Well, in terms of the regular season the 162 game schedule pretty much ensures the better teams will make the playoffs (and only 8 teams get in) so each of those would point to a particular type of team being successful, the big market big budget teams. However the fairest draft system in professional sports coupled with the most elaborate minor league system allows for the development of cheap talent which is usable for 5-6 years allowing the rise of previously always terrible teams like the Tampa Bay Rays. There are a couple of teams that are almost always terrible but at least it isn't half or one fourth the league like the other 2 sports.
Ignoring the regular season why is it more random teams win the World Series than not. As Billy Beane would say "It's fucking luck!," in general because hitters always have a higher failure rate at the plate than success (and failing 6/10 times is considered excellent) it is quite random over a small sample size how well one particular team will do against another. Hence this year where the Phillies lost to the Giants and the Yankees lost to the Rangers and the Rangers lost to the Giants in the World Series, thus ensuring that from the Championship series onward the underdog won every single game.
The best team in the league might have at most a 35% chance of winning the world series upon getting into the championship series and the worst team will have at worst a 15% chance. (unless they're the Gardenhire Twins or the Bobby Cox Braves of course) While the playoffs are something of a crapshoot (particularly the Division series) it is still quite entertaining every year to see different teams succeeding. At any rate baseball is definitively the fairest sport over the past 10 years, no salary cap and very little disincentive to spend as much as you want if you're the Yankees or Red Sox.