Deals between rivals

[TheGift23]

There are more in the article, I just took what I thought were the notable ones :

MLB
December 10, 1984 -- Gary Carter from Montreal to New York Mets:  The Mets acquired Carter from fellow NL East members Montreal for four players, Hubie Brooks, Mike Fitzgerald, Herm Winningham and Floyd Youmans.


NHL
August 9, 1988 -- Wayne Gretzky from Edmonton to Los Angeles:  In perhaps the biggest trade in NHL history, the Oilers sent Gretzky, plus Marty McSorley and Mike Krushelnyski to the Smythe Division foe Kings for Jimmy Carson, Martin Gelinas, three first round draft picks and cash.

NBA
October 20, 1976 -- Julius Erving from New York Nets to Philadelphia: Hit hard by their NBA entry fee and territorial damages from the Knicks as part of the NBA-ABA merger, the Nets sold future Hall of Famer Julius Erving to one of their new Atlantic Division rivals, the Philadelphia 76ers. Erving helped the 76ers reach the NBA Finals in 1976-77. The Dr. J-less Nets would finish that season an NBA-worst 22-60.


NFL
December 1961 -- Bobby Mitchell from Cleveland to Washington:  The Browns and ******** were then both members of the NFL's Eastern Conference. Mitchell, a future Hall of Famer, was dealt by Cleveland, which also had Jim Brown at the time, for Ernie Davis, the top pick in the 1962 NFL draft, then held in December of 1961. Mitchell was the first African-American player acquired by the ******** and Davis never played a down in the NFL, dying of leukemia in May of 1963.
Rest...

 

[jumpmanfromdabay]

--Babe Ruth from Red Sox to Yankees

 

[parasight21]

Originally Posted by JumpmanFromDaBay

--Babe Ruth from Red Sox to Yankees

/thread
not in American sports but Luis Figo's move from Barcelona to Real Madrid opened up the hell for Barcelona fans.