At 36, first-time closer Jason Grilli has an NL-best 29 saves for the wild-card-leading Pirates. (Hunter Martin/Getty Images)

One of baseball's best stories and one of its best players grace two separate covers of Sports Illustrated this week. The national cover features the Pittsburgh Pirates. Led by a bullpen that is nicknamed "The Shark Tank" and is anchored by All-Star closer Jason Grilli, the Bucs look like a strong bet to end their streak of 20 consecutive losing seasons. SI staff writer Ben Reiter chronicles how Pittsburgh is falling in love with baseball all over again and whether the Pirates have what it takes to reach the postseason for the first time in 21 years.

Buster Posey was last on SI's cover after his Giants won the 2010 World Series, the first of two titles for San Francisco in the past three years. (John Burgess/SI)

The postseason is certainly nothing new for the San Francisco Giants, winners of two of the last three World Series, or for their biggest star. Catcher Buster Posey has been so good, so young -- at 26, he's already won a Rookie of the Year and an MVP award, owns a .316 career batting average and has backstopped San Francisco's two title teams -- that he calls to mind another superstar with a similarly robust resume in his first few seasons: Derek Jeter. SI senior writer Tom Verducci has the story of why Posey is baseball's most indispensable player.

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