The award was decided by an online vote.
Here is the official news release from Major League Baseball about the award:
"Roy Halladay of the Philadelphia Phillies has been named the recipient of the "2010 Major League Baseball Clutch Performer of the Year Award Presented by Pepsi", it was announced today. Halladay is the winner of the officially-sanctioned Major League Baseball award, as voted by the fans, which recognizes the player who performed his best when the game was on the line.
"This year's MLB Pepsi Clutch Performer of the Year Award nominees were: Miguel Cabrera, Detroit Tigers; Roy Halladay, Philadelphia Phillies; CC Sabathia, New York Yankees; Rafael Soriano, Tampa Bay Rays; Joey Votto, Cincinnati Reds; and Brian Wilson, San Francisco Giants.
"In his first season in Philadelphia, Halladay posted a 21-10 record and a 2.44 ERA for the Phillies, who won their franchise-best fourth straight National League East crown. Halladay's 21 wins tied for Major League lead and he paced Major League Baseball with 250.2 innings pitched, nine complete games and four shutouts. He became the first Phillies pitcher to win at least 20 games in a single-season since Hall of Famer Steve Carlton went 23-11 in 1982 and the first right-hander to accomplish that feat since Hall of Famer Robin Roberts went 23-14 in 1955. "Doc" struck out 219 batters in his 33 regular season starts while walking only 30. After going 4-1 with a 1.80 ERA in April, the Denver native made history on May 29th at Florida, when he tossed baseball's 18th perfect game of the modern era, fanning 11 Marlins among his 27 consecutive outs to outduel fellow All-Star Josh Johnson in a 1-0 win. In July, Halladay was named an All-Star for the seventh time in his career and the first time as a National Leaguer. In the second half, Halladay put up an 11-3 record, highlighted by a 5-0 September, when he helped the Phillies seal the best record (97-65) in Major League Baseball for the first time in club history. Halladay excelled against the N.L. East rival Atlanta Braves with a 3-0 record and a 1.44 ERA. Against the N.L. East as a whole, Halladay posted a 14-1 mark and a 1.61 ERA in his 15 starts, including five complete games. Halladay's 14 wins against the N.L. East were the most by any pitcher in a single season since the start of the three-division format in 1994 and the most since Greg Maddux, then a Cub, also won 14 against the N.L. East in 1992. Halladay closed the regular season with a two-hit shutout against Washington, which clinched the N.L. East title for the Phillies. The durable veteran went seven innings or more in 28 of his 33 starts. Halladay allowed one earned run or less in 16 of his 33 starts and permitted two earned runs or less in 20 of his 33 starts. Halladay held opponents to .173 batting average (32-185) with runners in scoring position this season, the lowest mark among all N.L. pitchers, and he did not allow a hit with the bases loaded all season, holding opponents to an 0-for-7 mark. Halladay has pitched six or more innings in 55 consecutive starts on the road, the longest streak by any Major League pitcher since Hall of Famer Walter Johnson threw six innings or more in 82 consecutive road starts from 1911-1915.
During October, Major League Baseball fans voted for the award on pepsiclutch.mlb.com, a site powered by MLB.com, the official website of Major League Baseball, and created specifically for the MLB Clutch Performer Platform.
Monthly winners of the 2010 Major League Baseball Pepsi Clutch Performer of the Month awards include: Albert Pujols, St. Louis Cardinals (April); Brooks Conrad, Atlanta Braves (May); Mariano Rivera, New York Yankees (June); Buster Posey, San Francisco Giants (July); Joe Mauer, Minnesota Twins (August); and Alex Rodriguez, New York Yankees (September).
Previous winners of the "Major League Baseball Clutch Performer of the Year Award Presented by Pepsi" include Alex Rodriguez (2007), CC Sabathia (2008) and Andre Ethier (2009).