Players spend six months working their way through hot and cold streaks hoping to finish the year with solid all-around numbers. But it's just a few weeks in October that can cement a player's legacy in the eyes of both fans and the history books.
Some postseason heroes were already established stars. Others seemingly came out of nowhere for a well-timed surge. But there are a handful of performances that stand above the rest. Win probability added (WPA), which quantifies the changes in a team's chances of winning from one play to the next, is one effective way (though not the only way) to "rank" a player's contributions over the span of one October. The list of top peformers by this measure contains plenty of starpower -- along with a few names you might not expect.
Here's a look at the "most clutch" single-season performances, by WPA, in postseason history.
1-T. David Ortiz, 2004, Red Sox (1.9 WPA)
Big Papi established himself as an October legend when he posted a .400/.515/.764 line while helping Boston end its 86-year World Series title drought. Along the way, he won ALCS MVP as the Red Sox became the first (and still only) team to come back from a 3-0 deficit in a seven-game series -- and did so against the arch-rival Yankees.
Top moment: Walk-off home run in Game 4 of ALCS vs. Yankees.
1-T. David Freese, 2011, Cardinals (1.9 WPA)
Freese drove in four runs against the Phillies to force a decisive fifth game in the NLDS, then hit .545 with three homers against the Brewers en route to NLCS MVP honors. But Freese was most electric in Game 6 of the World Series against Texas, when he tied the game with a two-run triple in the ninth with St. Louis down to its final strike of the season, and then knocked a walk-off home run to center field in the 11th. Freese's two-run double in Game 7 gave him a record 21 RBIs in a single postseason as the Cardinals pulled off an unlikely championship.
Top moment: Game-tying triple and walk-off homer in Game 6 of World Series vs. Rangers
3-T. Curt Schilling, 2001, D-backs (1.8 WPA)
Rounding into his peak form at age 34, Schilling allowed just one earned run over two complete-game wins against the Cardinals in the NLDS, and then held the Braves to one run in another complete-game victory in Game 3 of the NLCS. The righty made three starts against the Yankees in Arizona's first World Series, allowing just four runs over 21 1/3 innings before Randy Johnson and Luis Gonzalez closed out the D-backs' dramatic Game 7 victory.
Top moment: Complete-game win in decisive Game 5 of NLDS vs. Cardinals
3-T. Alex Rodriguez, 2009, Yankees (1.8 WPA)
Rodriguez had plenty to prove after empty postseason trips with the Yankees in 2004-07, including a stretch beginning in Game 4 of the '04 ALCS in which he went 0-for-29 with runners in scoring position. But oh, did A-Rod deliver in '09. Rodriguez hit game-tying homers in Games 2 and 3 of the ALDS against the Twins, then struck another game-tying dinger in the 11th inning in Game 2 of the ALCS against the Angels. But Rodriguez wasn't done; the three-time MVP came up big again in the World Series with a go-ahead double off Phillies closer Brad Lidge in the ninth inning of Game 4 to help the Yankees clinch title No. 27.
Top moment: Game-tying, ninth-inning HR in Game 2 of ALDS vs. Twins
5. Carlos Beltran, 2013, Cardinals (1.6 WPA)
Beltran's eight-homer October with the Astros in 2004 is probably remembered more, but his glove proved just as clutch for the Cardinals' NL pennant run eight years later. The 36-year-old Beltran threw out Dodgers second baseman Mark Ellis at home plate in the 10th inning to keep Game 1 of the NLCS tied and then hit walk-off single in the bottom of the 13th. Beltran robbed Ortiz of a grand slam in Game 1 of his first World Series, injuring his ribs in the process, but continued playing and finished the Cardinals' six-game defeat with a .294 average and three RBIs.
Top moment: Outfield assist and walk-off single in Game 1 of NLCS vs. Dodgers
6-T. Madison Bumgarner, 2014, Giants (1.5 WPA)
There might not be a better example of a pitcher putting a team on his shoulders than Bumgarner, who tossed a record 52 2/3 innings for the Giants in October '14. After shutting out the Pirates in the NL Wild Card Game, Bumgarner earned wins in Games 1 and 5 of the NLCS against the Cardinals before submitting a World Series for the ages against Kansas City. MadBum permitted one run across victories in Games 1 and 5, then turned around on two days' rest to come out of the bullpen and record a five-inning save in Game 7 -- the longest save in a winner-take-all postseason game in history.
Top moment: Five-inning save in Game 7 of World Series vs. Royals
6-T. Eric Hosmer, 2014, Royals (1.5 WPA)
After playing for several years in the Royals' rebuilding efforts, Hosmer got his first taste of the postseason in '14 and took full advantage. The first baseman reached base five times and scored the game-tying run after tripling in the 12th inning of K.C.'s thrilling Wild Card Game victory over the A's, and then knocked a two-run, 11th-inning dinger against the Angels that proved to be the difference in Game 2 of the ALDS. Though the Royals finished a run shy of a World Series title, Hosmer finished that October with a sterling .351/.439/.526 slash line.
Top moment: Go-ahead, two-run homer in 11th inning of Game 2 of ALDS vs. Angels
6-T. John Wetteland, 1996, Yankees (1.5 WPA)
Before Mariano Rivera became the most dominant closer in history, he played setup man to a brilliant Wetteland during the first year of the Yankees' dynastic 1990s run. The right-hander converted each of his seven save opportunities and helped New York win five different games by two runs or less -- including its decisive Game 6 victory over the Braves in the World Series.
Top moment: Save in Yankees' 3-2 win in decisive Game 6 of World Series vs. Braves
6-T. Bernie Williams, 1996, Yankees (1.5 WPA)
Williams powered the Yankees to their first World Series title in 18 years, beginning with his .467 average and three homers against Texas in the ALDS. The center fielder stayed hot in the next round, belting a walk-off homer in the 11th inning of Game 1 and hitting .474 for the series to help New York vault past the Orioles and into the Fall Classic. Though he hit much worse in the World Series, Williams did belt a clutch two-run homer in Game 3 -- a must-win game with his club down two-games-to-none in the Series.
Top moment: Walk-off home run in Game 1 of ALCS vs. Orioles
10-T. Waite Hoyt, 1921, Yankees (1.4 WPA)
Babe Ruth and Lou Gehrig garnered the lion's share of attention for the Yankees' dominant 1920s teams, but the club also boasted a Hall of Fame ace in Hoyt. The right-hander's complete-game performances in Game 2, 5 and 8 -- in which he did not allow a single earned run to the Giants -- rank right alongside Christy Mathewson and Sandy Koufax for the most dominant in World Series history. Hoyt's heroics might be remembered even more had the Yankees won this Fall Classic; the Giants claimed his final start, 1-0, thanks to a first-inning error by Yankees shortstop Roger Peckinpaugh.
Top moment: Complete-game victory in Game 5 of World Series vs. Giants, giving Yankees a three-games-to-two lead
10-T. Cliff Lee, 2009, Phillies (1.4 WPA)
The Phillies made a statement in vying for their second straight pennant when they traded four players (including Carlos Carrasco) to the Indians for Lee, the reigning AL Cy Young winner, before the 2009 Trade Deadline. The southpaw responded with a brilliant run in his first October, leading Philly to wins in all three of his three combined starts in the Division and Championship Series. Lee then twirled one of the most dominant World Series starts in Game 1 against the Yankees, allowing one unearned run while striking out 10 without walking a single batter in a complete-game effort. New York solved Lee in Game 5, but his first four outings remain brilliant in retrospect.
Top moment: A 10-strikeout, complete-game victory in Game 1 of World Series vs. Yankees
10-T. Mariano Rivera, 1999, 2000 and 2003, Yankees (1.4 WPA)
You don't become one of the best postseason performers in history without sustained excellence, and that's why Rivera owns three of the top Octobers by WPA. The Yankees closer converted all six of his postseason save opportunities in both 1999 and 2000, and his three scoreless innings against Boston in Game 7 of the 2003 ALCS are overshadowed by Aaron Boone's dramatic walk-off home run.
Top moment: Three scoreless outings en route to MVP honors in 1999 World Series vs. Braves
Matt Kelly is a reporter for MLB.com based in New York. Follow him on Twitter at @mattkellyMLB.