Babe Ruth: The ultimate example came in January 1920, when Red Sox owner Harry Frazee sold Ruth to New York for $100,000 and a $350,000 loan to finance Frazee's Broadway production interests. Ruth had won 89 games as a pitcher for Boston over six seasons, and with the Yankees, he defined slugging. The "Sultan of Swat" converted to the outfield full-time after his sale to the Yankees and led New York to seven American League pennants and four World Series titles -- finishing with 714 home runs and leaving a long-lasting "Curse of the Bambino" in baseball lore.
Wade Boggs: The hitting virtuoso won five batting titles while starting his career with the Red Sox from 1982 to 1992, but what he never won was a World Series championship there. That changed after he put on pinstripes. Boggs signed as a free agent with the Yankees in 1992, and in 1996, he had three hits in a World Series that New York won over Atlanta in six games to start what would become a dynasty. Boggs celebrated on horseback at Yankee Stadium, and he would finish his career with 3,010 hits and induction at Cooperstown last summer.
Herb Pennock: The "Knight of Kennett Square" made the difficult jump directly from high school, joining the Philadelphia A's in 1912. Three years later, Connie Mack sold him to the Red Sox. The Sox traded Pennock to the Yankees in 1923, and he went 5-0 in World Series competition for New York. Miller Huggins called him the greatest left-hander in baseball history at the time, and he was inducted into the Hall of Fame in 1948.
Waite Hoyt: The right-hander was a 19-year-old teammate of Ruth on the 1919 Red Sox, and he joined Ruth on the Yankees for the 1921 season. That launched Hoyt's Hall of Fame career. He pitched three games in that 1921 World Series and allowed only two runs, earning two of his six career World Series victories. He was a mainstay of six Yankees pennant winners in the 1920s.
Sparky Lyle: As a rookie in 1967, Albert Walter Lyle made 27 appearances for a Red Sox team that would go to the World Series. He began to emerge the next year as the team's bullpen ace, but before the 1972 season, he was traded straight-up for Danny Cater. It was an ill-fated move by the Red Sox. Lyle was part of a World Series champion in 1977 and 1978, and in the former year he became the first reliever to win the American League Cy Young Award.
Red Ruffing: Ruffing played for the Red Sox from 1924 to 1930, but he had an abysmal 39-96 record during that stretch. His career blossomed when he was traded to the Yankees. An instrumental part of seven pennant winners, Ruffing won seven of nine World Series decisions. His 273 career victories include a four-year stretch (1936 to 1939) in which he won at least 20 games per season. He was a 1967 Hall of Fame inductee.
Carl Mays: After pitching alonside Ruth on Red Sox champions, he was traded to the Yankees for Allen Russell, Bob McGraw and $40,000. Mays won a combined 53 games in his first two full seasons in the Bronx, and played on two more World Series clubs with Ruth while in New York.
Danny MacFayden: "Deacon Danny" was a native New Englander who seemed to have it all in starting a 17-year Major League career with his local Red Sox. He pitched for them from 1926 to 1932, and that included a 16-12 campaign in 1931. But he was dealt to the Yankees on June 5, 1932, for Ivy Andrews, Hank Johnson and $50,000. That means he got to enjoy being in pinstripes when Ruth hit his legendary "Called Shot" homer in the 1932 World Series at Wrigley Field.
Luis Tiant: One of the most colorful characters in Red Sox history, the sidewinding righty from Cuba had three 20-win seasons in Boston and helped the Sox to the 1975 World Series against Cincinnati. In 1978, he was part of a Sox team that saw Bucky #%*$& Dent hit a fabled homer at Fenway to put the Yanks into the playoffs. Tiant was granted free agency that November and signed with the Bombers, but his good years were mostly behind him and he won 13 games in 1979 and eight the next season.
(Reader Ron Melcher faithfully notes that Don Zimmer -- who would ultimately coach for Joe Torre in the Yankees dugout and have the memorable set-to with Pedro Martinez -- was Boston's "fiery manager when Bucky Dent hit that Sox-killing home run.")
Babe Dahlgren: The first baseman had an outstanding rookie season with the Red Sox in 1935, driving in 63 runs while playing in 149 games. He was displaced in 1936 when Boston acquired Jimmie Foxx, then dropped to the Minors, and in 1937, he played third base for the championship Newark club of the International League. The Yanks purchased his contract from the Red Sox, and on May 2, 1939, Dahlgren played first base for the Bronx Bombers in place of the ailing Lou Gehrig -- thus officially ending the consecutive-game streak of the Iron Horse at 2,130. Dahlgren homered that day and remained the Yankees' first baseman for two seasons.
Everett Scott: The durable shortstop had teamed with Ruth on three champion Red Sox teams (1915, 1916 and 1918), and he also followed the Bambino trail to New York. He was traded by the Red Sox on Dec. 20, 1921, along with Joe Bush and Sam Jones, in exchange for Roger Peckinpaugh, Jack Quinn, Rip Collins and Bill Piercy. Scott played for the Bombers in the 1922 and 1923 World Series, helping them to victory in the latter after hitting .318 in the series against the Giants.
Roy Johnson: This one is a little more of an indirect transition from Red Sox world to Yankees world. Johnson, an outfielder, had driven in 119 runs for the 1934 Red Sox. On Dec. 17, 1935, he was traded with Carl Reynolds to the Washington Senators for Heinie Manush. On Jan. 17, 1936, the Sens then traded him to the Yankees with Bump Hadley for Jimmie DeShong and Jesse Hill. Johnson's contribution in pinstripes wasn't much, but if you were a Yankee back then, there was a good chance you would win a World Series championship. That's what happened in 1936, when Johnson appeared in 63 games during another title season.
Joe Dugan: "Jumping Joe" was the third baseman for the '27 Yankees, generally considered the greatest baseball team of all-time. In July 1922, he had been dealt by the Red Sox along with outfielder Elmer Smith to the Yankees for shortstop Johnny Mitchell, reliever Lefty O'Doul, outfielder Elmer Miller, utility man Chick Fewster and cash. Dugan, one of the better defensive third basemen in the league, hit .286 over seven seasons with the Yanks (winning three world championships). Fewster, Miller, and Mitchell combined for 717 at-bats, and O'Doul appeared in 23 games (1-1, 5.43 ERA) for Boston in 1923.
Obviously jumping from the Red Sox to the Yankees was more prone to happen back in those days, simply because MLB was a more intimate family back then. But it's worth noting that when the Yankees won their first world championship in 1923, there were 11 players on their roster who had come from the Red Sox -- led, of course, by Ruth.
Roger Clemens technically doesn't count for the purposes of this exercise, but it was still hard to imagine him in pinstripes if you were a Red Sox fan earlier in his career. The Rocket pitched his first 13 seasons for Boston, won a combined 41 games over the 1997 and 1998 seasons with Toronto, and then had that five-year run (with four World Series trips) with the Yanks.
Ironically, it was just last season that Mark Bellhorn went from the Red Sox to the Yankees. It would have been a little hard to imagine that the previous October, when he was playing a key role during that historic comeback for Boston in the American League Championship Series. But now here comes Damon to the Bronx, a far bigger impact, and that's one that's worth a trip back into the rivalry books.