They found that age and postseason experience had no effect on a team’s chances; surprisingly, they also found no significant correlation between any measure of team offense (including bunting and stealing) and postseason success. What they did find important were three measures of pitching and defense, which they called the “Secret Sauce”.
The best predictors of October glory are a pitching staff with a high strikeout ratio, a strong team defense and a solid closer. Since scoring is depressed in the postseason, it's valuable to have a pitching staff that avoids bats, a defense that can save runs and a closer than can lock down victories. Jaffe does a great job of explaining in detail why these factors increase in importance in the playoffs and concludes (emphasis mine):
None of this is meant to knock the offense, which has helped make them a near-lock for the playoffs. But it’s the Secret Sauce that bodes well for their chances once they get there. The last time the team made such a drastic leap in the Sauce rankings was 1996—which, fans will remember, was the end of their last excruciatingly long World Series drought.
Since Jaffe is a BP guy, he's not concerned with jinxes and is speaking in no uncertain terms because their odds have the Yanks' odds of making the postseason are at 99.4%.
The leap he's talking about comes mainly from a jump from 26th to 3rd in Fielding Runs Above Average and a big boost in K/9. The increase in strikeouts is obviously driven by the acquisitions of CC Sabathia and A.J. Burnett but the cosmic leap in defense is harder to explain. Even with Derek Jeter suddenly above average at short and Hideki Matsui, Jason Giambi, and Bobby Abreu out of the field all together it's hard to imagine the Yankees jumping 23 slots in that ranking.
Do I trust the rankings implicitly? No, but it certainly is encouraging to know that the Yanks have a team built for success not only in the regular season, but into October as well. Whether or not that translates into anything this year remains to be seen. Those are the chickens that Jaffe doesn't dare to count either.