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After coming up short against the Boston Red Sox in the 2013 World Series, the St. Louis Cardinals entered the offseason with a very specific to-do list.

At the top of that list: adding a productive shortstop.

With the regular season in the books, it’s safe to say the Cardinals found what they were looking for in Jhonny Peralta.

The .222 batting average and four home runs from Cardinal shortstops in 2013 ranked 14th among all National League teams, while the duo of Pete Kozma and Daniel Descalso combined for a dismal minus-0.2 WAR.

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Two of the American League’s top teams will square off when the Los Angeles Angels take on the Kansas City Royals in the American League Division Series.

The series starts at Angel Stadium, with Game 1 scheduled for Thursday at 9 p.m. ET on TBS.

The Angels ran away with the AL West crown to make the postseason for the first time in the last four years, as the team won an MLB-leading 98 games while also posting the game's best home record (52-39). Beyond that, the Angels offense ranked third in the AL in batting average (.259), fourth in slugging (.406) and OPS (.728) and tied for fourth in home runs (155) with the White Sox and Tigers.

Meanwhile, the Royals are coming off a dramatic win in the AL Wild Card Game, as they defeated the A’s 9-8 in 12 innings in front of an electric crowd at Kauffman Stadium.

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The 2014 MLB postseason continues Wednesday with the Pittsburgh Pirates set to host the San Francisco Giants in the National League Wild Card Game (8:00 p.m. ET, TV: ESPN).

Pittsburgh captured the top NL wild-card spot to secure its second consecutive postseason berth, finishing two games back of the division-winning St. Louis Cardinals in the NL Central.

San Francisco is returning to the playoffs for the third time in the last five years after tying the Pirates in the wild-card race and finishing six games behind the Dodgers in the NL West.

The Pirates clinched home-field advantage by winning the regular-season series against the Giants 4-2, as they took two of three games in both of their meetings. Overall, they outscored the Giants 29-23.

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Having a breakout season is a challenge for most players. Pulling it off in the postseason, when playing time is limited and every next play could potentially determine the season, is another story.

However, every year there are players who do just that, as they go from little-known prospects or under-appreciated veterans to playoff heroes and household names seemingly overnight.

With the playoff games set to begin Tuesday night, it’s time to preview some of the players who appear primed for a breakout performance this October.

Here’s a look at the biggest potential breakout stars for the 2014 postseason.

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The 2014 MLB postseason begins Tuesday, with the Kanas City Royals set to host the Oakland Athletics in the American League Wild Card Game (8:07 p.m. ET, TV: TBS).

Kansas City captured the top AL Wild Card spot to secure its first postseason berth in 29 years, and came within one game of the division-winning Detroit Tigers in the AL Central.

Oakland is returning to the playoffs for the third straight year after finishing one game back of Royals in the Wild Card.

The Royals won the regular-season series against the A’s, 5-2, taking two of three games in Oakland during their first meeting (Aug. 1-3), and then winning three of four at Kauffman Stadium (Aug. 11-14).

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With the regular season coming to an end in a matter of days and the postseason set to begin next week, every playoff team will soon be forced to make difficult decisions regarding its roster.

The number of players a team can roster will drop from the 40 previously allowed in September back to the standard 25 next month. As a result, teams will craft their postseason rosters based on their own strengths as well as the perceived weaknesses of their upcoming opponent.

Many of baseball’s top rookies have a realistic chance of cracking their team’s postseason roster this year, though there will be even more players denied the opportunity to play in October.

Here are five rookies who could carve out huge roles in the 2014 postseason.

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When things get tight at the end of the MLB season, some players show up and guide their teams into the playoffs.

Last season, it was right-hander Michael Wacha, who joined the St. Louis Cardinals starting rotation in early September and subsequently became one of the biggest stories of the postseason, as the rookie took home NLCS MVP honors and pitched his team into the World Series.

Meanwhile, right-hander Gerrit Cole was just as dominant for the Pittsburgh Pirates last season, as the flame-throwing rookie solidified the starting rotation down the stretch and played a major role in his club’s long-overdue postseason berth.

But those are just a couple of unique examples. The reality is that every team fighting for a playoff spot likely has its share of heroes.

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It’s quickly becoming clear why the Boston Red Sox shelled out big bucks last month to sign Cuban outfielder Rusney Castillo.

Castillo connected for his first major league home run in the third inning of Thursday’s 11-1 win over the Tampa Bay Rays, blasting a three-run shot into the seats above the Green Monster in left-center field.

He has continued to showcase his immense potential in the first two games of the weekend series against the rival New York Yankees, going 5-for-6 with a home run and two RBI through Saturday. 

The Red Sox made Castillo the highest-paid Cuban player in baseball history last month, signing the 27-year-old outfielder to a seven-year, $72.5 million contract through the 2020 season.

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This year’s September call-ups’ brief taste of the major leagues might be coming to an end, but it goes without saying that their futures are increasingly bright.

For the better part of the last month, we’ve been highlighting the top call-ups across baseball, whether it be breaking down their early returns in the major leagues or their potential impact on the playoff races.

Today, however, we’re going to look at the very best September call-ups—specifically, prospects that appeared in our recent end-of-year top 100 prospect rankings—by assigning grades for each player’s overall season while also considering how their performances might affect their respective 2015 outlooks.

With all that being said, here are the grades and projections for Major League Baseball’s top September call-ups.

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For the second straight year, the Los Angeles Dodgers are National League West champions.

Led by another strong performance from probable NL Cy Young Award winner and legitimate MVP candidate Clayton Kershaw, the Dodgers trounced the San Francisco Giants 9-1 in front of a sold-out Dodger Stadium to secure home-field advantage in the NLDS.

Though it wasn’t his sharpest outing, Kershaw allowed just one run on eight hits over eight innings in his final start of the regular season, striking out 11 batters without issuing a walk. The win was the left-hander’s 21st of the season, matching his career high from 2011, and he reached the mark in just his 27th start.

Kershaw also helped his cause by going 1-for-2 with an RBI triple, and he made a potentially game-saving play with no outs in the third inning when he fielded a hard-hit, comeback ground ball behind his back to prevent at least one run from scoring.