They say some of the best trades are the ones you didn't make. Here are some of the trades GMs wish they hadn’t.
1910 – The Cleveland Naps trade outfielder Bris Lord to the Philadelphia Athletics for outfielder Joe Jackson. The Athletics played Jackson for a total of 10 games before they gave up on him. Lord was fine for a season and a half before he fell apart. As for Jackson, he became arguably the greatest pure hitter in baseball history...before tragedy would destroy his career in 1920.

December 11, 1959 – The Kansas City Athletics trade outfielder Roger Maris, first baseman Kent Hadley, and infielder Joe DeMaestri to the New York Yankees for pitcher Don Larsen, outfielder Hank Bauer, first baseman/outfielder Norm Siebern, and utilityman Marv Throneberry.
For much of the ’50s and ’60s, the Athletics might as well have been a farm system team for the Yankees. However, the A’s thought they were making a good deal here. They were trading a young player who had put up some nice numbers, but wasn't projected to be a star, and would package him with a pair of busts. However, Maris would blossom into a star – winning the MVP Award in ’60 and ’61. As for what the A’s got, almost all were busts or aging players, only Siebern would do well.
1964 – The Chicago Cubs trade outfielder Lou Brock, pitchers Jack Spring and Paul Toth to the St. Louis Cardinals for pitchers Ernie Broglio, Bobby Shantz and outfielder Doug Clemens. Five of the players exchanged never amounted to anything, while Brock became one of the all time greats. He finished the last 16 years of his career with the Cards, winning two World Series, and was inducted into the Baseball Hall of Fame.
1965 – The Cincinnati Reds traded Frank Robinson to the Baltimore Orioles for Jack Baldschun, Milt Pappas, and Dick Simpson. This was a case of a great player getting traded, he was great before the trade, great after it. He helped the O’s win a World Series in his first season with the team, and another in ’70. The Reds may not have gotten equal value, but the ’70s were pretty good to them, so they probably didn't lose too much sleep over this one.
1966 – The Chicago Cubs trade pitchers Larry Jackson and Bob Buhl to the Philadelphia Phillies for pitcher Fergie Jenkins, and outfielders John Herrnstein and Adolfo Phillips. Jenkins was a talented young player who would be dominant for years, eventually winding up in the Hall of Fame. In return, the Phillies got two starters that were 35 and 37 years old and were clearly on the downsides of their careers. Jackson would be decent for three years in Philly rotation but Buhl would last just 137.1 innings and win 6 games in slightly over one year with the Phils. After Leo Durocher converted Fergie to a starter, he would win twenty games in six straight seasons.
1971 – The Houston Astros trade Joe Morgan, Ed Armbrister, Jack Billingham, Cesar Geronimo, and Denis Menke to the Cincinnati Reds for Tommy Helms, Lee May, and Jimmy Stewart. Judging by the stats, Morgan was a solid 2nd baseman for the Astros, but nothing out of this world. Then the season he got traded to the Reds he became one of the best players in baseball.

1971 – The New York Mets trade pitchers Nolan Ryan, Don Rose, catcher Frank Estrada, and outfielder Leroy Stanton to the California Angels for shortstop Jim Fregosi. The Mets thought that Fregosi would be their answer to upgrade their infield. And they probably thought that they got away with a steal, including Ryan, a wild, but talented player, and a bunch of busts in the deal.
1982 – The Chicago Cubs trade Ivan DeJesus to the Philadelphia Phillies for Larry Bowa and second baseman Ryne Sandberg. Brought into replace the aging Larry Bowa, DeJesus lasted just three mediocre seasons in Philly before flaming out with the Cardinals. Bowa did nicely in Chicago until he finished his career in New York. The real steal for the Cubs here was Sandberg, the future Hall of Famer.
1982 – In a six player deal, the San Diego Padres trade shortstop Ozzie Smith to the St. Louis Cardinals for shortstop Garry Templeton. Seeking an offensive upgrade at short, the Padres swapped Smith, who remained the quality player that he had been and would be throughout his career, for Templeton.

1989 – The Montreal Expos trade pitchers Randy Johnson, Gene Harris, and Brian Holman to the Seattle Mariners for pitchers Mark Langston and Mike Campbell. The Expos got robbed. This deal wouldn't have been a good one even if Langston, who was a pretty good pitcher, had remained in Montreal. Campbell, he would never play for the Expos. And in return, they gave up on a control-plagued Randy Johnson, who would blossom into a Hall of Fame pitcher, and on Holman, who was a good pitcher in his short time in baseball. Had the Expos kept Johnson, they would have had one of the best one-two punches with Johnson and Pedro Martinez.

1993 – The Los Angeles Dodgers trade pitcher Pedro Martinez to the Montreal Expos for Delino DeShields. A trade brought on by necessity. Pedro would dominate the National League and was a part of that magical 1994 Expos team that would have won the World Series before he became a part of the Red Sox. DeShields wasn’t even a top second baseman, and Pedro was already on the winning track after his rookie year. Dumb.
1997 – The Oakland Athletics trade first baseman Mark McGwire to the St. Louis Cardinals for pitchers T.J. Matthews, Blake Stein, and Eric Ludwick. This was highway robbery. Oakland, seeking to get McGwire’s deal off the books while at the same time obtaining young starting pitching, saw this deal as a way to help improve their rotation dramatically. Oh how wrong they were. Of the three, only Matthews would work out, and even he was mediocre, his best season coming in 1999 (9-5 with a 3.81 ERA). McGwire would energize the Cardinals, giving them a force in the lineup to go along with Jim Edmonds and Edgar Renteria.
1998 – The Houston Astros trade pitchers Freddy Garcia, John Halama and infielder Carlos Guillen to the Seattle Mariners for pitcher Randy Johnson. Halama and Guillen were average players, but Garcia became an ace for the Mariners for many years, before he got sent to the White Sox. As for Johnson, Johnson became the ace of the greatest Astros team in history, but he would leave for a big money contract with the Diamondbacks.