In brief, a few reasons to hope the Rockies overcome the odds and spare us the sanctimony of Red Sox Nation:
Coors Field: Even in the days when they were awful, the Rockies have always been a formidable foe at home in the rare air of Denver. The park doesn't play as severe as it once did, thanks to the use of a humidor, but it still packs a wallop on unfamiliar foes. As the Minnesota Twins can tell you, being dominant at home is a great card to have in your pocket in a short series. Unlike those Twins teams, the Rockies don't have the four games at home, but they should have enough to drag out the series and bring it down to the final games where anything can happen. Then there is Coors' famously cavernous outfield....
Defense: The Rockies are not "the best fielding team of all time," which is widely touted in the press because of their all-time high fielding percentage, but they are awfully good, and certainly a fair shot better than the Sox, especially if Boston resorts to playing David Ortiz in the field during the middle three. And there is Manny Ramirez, who may get lost in the Coors outfield and never return. The Rockies defense should also help them to adapt better to Fenway, where they also played a three-game series during the regular season.
A serviceable DH: It's my opinion that AL teams have a bigger advantage regarding DH maneuvering in the World Series because they construct their team with an additional slugging first baseman, while NL teams often have to slot in a light-hitting utility player. Colorado, however, has Ryan Spillborghs available, a very respectable hitter who played most of the final two months of the season in center field.
The weather. Mother Nature is a great randomizer, and the chance for lousy weather in the World Series is once again high (honestly, how much more can the series be pushed back into late fall? Will we eventually have the Winter Classic?). The Rockies practiced in the snow last weekend, though at last check none is forecast for Denver this coming weekend. (Though with these things one should always be careful. Veterans are usually more reliable mudders, and Boston has many more of those.)
They're actually good: Winning 21 baseball games out of 22 is by definition a fluke. But the Rockies current run is also too long to be merely a fluke. A cursory glance at the talent the Rockies have assembled here makes you think they could easily win 95-100 games over a full season. They shouldn't be underestimated just because they needed a torrid run down the stretch (and a lot of help from elsewhere) to sneak into the playoffs.
It's the World Serious. Enough said about that.