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Playoffs not the time to rely on run differential

Regular-season results go out the window with unpredictability of October

You have heard that run differential is an exceptional predictor of baseball outcomes.

Not this October.

The team with the better regular-season run differential lost four of seven postseason series. For the record:

• In the American League Division Series, Baltimore (plus-112 run differential in the regular season) beat Detroit (plus-52). But Kansas City (plus-27) beat the Los Angeles Angels of Anaheim (plus-143).

• In the National League Division Series, San Francisco (plus-51) beat Washington (plus-131). And St. Louis (plus-16) beat Los Angeles (plus-101).

• In the Championship Series, run differential was merely a 50-50 proposition. Kansas City (plus-27) defeated Baltimore (plus-112) in the ALCS. San Francisco (plus-51) defeated St. Louis (plus-16) in the NLCS.

• In the World Series, run differential scored a victory when San Francisco (plus-51) defeated Kansas City (plus-27). On the other hand, with these sorts of run differentials, neither one of these Wild Card teams was supposed to be competing for the World Series championship in the first place.

These results do not include the Wild Card Game for the AL and NL on the grounds that, hey, anything can happen in one game. This has become the whole driving force behind the Wild Card Game. Whether you see it as a punitive measure directed at teams that did not win a division, or as a terrific dramatic device, two Wild Card teams advanced to the World Series for the first time since 2002.

And the Wild Card Game matchups themselves were not advertisements for run differential, either. In the NL, the Giants and the Pirates were each plus-51 in run differential in the regular season -- a tie. In the AL, the Athletics were run-differential kings at plus-157. So what? They lost to the Royals who were, as already noted, a mere plus-27.

Thus, for the entire postseason, the better run-differential teams were 3-5-1 in all rounds. That doesn't appear to be much of a sure thing, does it?

The oft-expressed notion that run differential is a better predictor of outcomes than won-loss records was accurate, but not in a particularly impressive kind of way. The teams with the better records were 2-6-1 in these postseason rounds. The World Series victory by the Giants (88-74) over the Royals (89-73) seemed to be much more about Madison Bumgarner's pitching than run differential or regular-season record.

On the surface, there wasn't much to pick from in that San Francisco-Kansas City matchup, except that in the postseason leading up to the World Series, these two teams were a combined 16-2.

If you want a governing theory for the postseason, it is not going to be run differential. It is going to be that it is not the better team that wins. It is the team that is playing better.

Admittedly, that concept cannot be reduced to a neat, numerical value. But it covers the wonderful unpredictability that baseball can take on in October and certainly did take on in this October.

Welcome to the San Francisco Giants and the Kansas City Royals, World Series winners and World Series runners-up. Of the 10 teams in the 2014 postseason, they ranked tied for seven and ninth, respectively, in regular-season run differential.

Mike Bauman is a national columnist for MLB.com.