On February 13, 1996, Walt Jocketty sent a minor league pitcher by the name of Steve Montgomery to Oakland in exchange for a 41-year-old future Hall of Famer by the name of Dennis Eckersley. The deal reunited Eckersley with Tony LaRussa and Dave Duncan who had converted him into a one of the most dominant relievers in all of baseball while they were in Oakland. His resume included a no-hitter, a 20 win season, six All Star appearances, an MVP Award, a Cy Young Award, and he was a World Champion as well. A deal that sent him to Oakland in 1987 was a game changer, as Duncan and LaRussa convinced him to move to the bullpen. The move was one that would pave a road to Cooperstown, New York. While we in St. Louis did not get to see him play in his prime the deal was still a good one as Eckersley locked down 66 saves in two seasons. Montgomery appeared in just 72 games over four seasons, and 53 of those came in 1999 with the Phillies. The Birds definitely won that deal, and the fans won as well because they got to watch another Hall of Famer wear those two birds on the bat.
Stats of a legend: http://www.baseball-reference.com/players/e/eckerde01.shtml