For six contenders, D is the key

Producing runs won't be an issue for Fielder and Cabrera, but saving runs on defense might be. Derick E. Hingle/US Presswire

Before the 2011 season, the St. Louis Cardinals jettisoned all-glove shortstop Brendan Ryan and brought in Ryan Theriot. Theriot proved that he could neither hit nor play shortstop well, so the Cardinals were forced to make a trade deadline deal to bring in veteran Rafael Furcal. Still a solid defensive shortstop at 33, Furcal represented an upgrade for an infield which struggled behind heavy ground-ball pitchers Jaime Garcia and Jake Westbrook.

Of course, the Cardinals made one of the more remarkable turnarounds in September history to squeak into the playoffs en route to their second World Series title this century.

While Theriot's defensive struggles nearly cost the Cardinals a shot at October, Furcal played a large part in the late-season surge. Here are six teams whose defense, good or bad, could make the difference in their playoff chances.

Teams whose defense could cost them a playoff spot

Detroit Tigers
While a lineup with Miguel Cabrera and Prince Fielder is intimidating, an infield featuring both hulking sluggers is far from it. In his last two seasons in Florida (2006 and '07), Cabrera played third base every day and cost the Marlins an estimated 29 runs (according to our runs saved metric) compared to an average third baseman. Around his 25th birthday, Cabrera played 14 games at third before the Tigers were forced to move him across the diamond to first base. Ever since, Cabrera has been a consistently below-average first baseman.