Jim Powell has brought the question up, when was the last time the Brewers made a mid-season trade that involved them giving up prospects in exchange for a veteran player to help the Crew win now after 1982?  Since I'm being paid to sit here and run the game behind the scenes, I did a little research.  I checked  www.baseball-reference.com and I couldn't come up with anything.  In fact, in terms of mid-season trades when the Brewers were actually somewhat in contention (I'm basing it on finishing near, at, or above .500) the Brewers really didn't do much.  Just take a look...

1983 (87-75 record)

Major transactions during the season

6/6/83 Traded Gorman Thomas, Jamie Easterly, and Ernie Camacho to the Cleveland Indians. Received Rick Manning and Rick Waits.

Manning went on to hit .229, Waits had 5.10 ERA in 30 innings pitched.

The Brewers also signed Juan Nieves on July 1st that year and at least he went on to throw a no-hitter a couple years later.

1987 (91-71)

Major transactions during the season

6/28/87 Traded Russ McGinnis to the Oakland Athletics. Received Bill Mooneyham.

That is about all I could come up with and Mooneyham didn't play a game for the Brewers.

1988 (87-75)

Major transactions during the season

6/8/88 Traded Ernest Riles to the San Francisco Giants. Received Jeffrey Leonard.

The Brewers did draft Pat Listach that season in the second round!

1989 (81-81)

Major transactions during the season 

7/31/89 Traded Brian Drahman to the Chicago White Sox. Received Jerry Reuss.

That is a name from the past, Reuss actually pitched in the first White Sox game I ever attended, he really didn't help the Sox then and didn't help the Brewers when he got to Milwaukee.

8/23/89 Traded a player to be named later to the Atlanta Braves. Received Ed Romero. The Milwaukee Brewers sent Jay Aldrich (September 1, 1989) to the Atlanta Braves to complete the trade. 

Romero hit .250 in 1982 in 52 games for the Crew, in his return trip, only played in 15 games hitting .200 with 3 RBI.  At least Aldrich did nothing (8.25 ERA with Baltimore in 1990).

1991 (83-79)

Major transactions during the season

They drafted Mike Matheny & Jeff Cirillo other than that, trading Candy Maldonado for a player to be named later on 8/9/91 was about the biggest move.  Oh, the Brewers drafted some player named Nomar Garciaparra although they didn't sign him.  I wonder what type of career Garciaparra went on to have?

1992 (92-70)

Major transactions during the season

7/7/92 Traded Jeff Kunkel to the Chicago Cubs. Received Ced Landrum. 

Landrum didn't even play that year and was with the Mets next season where he played a total of 22 games.

1996 (80-82)

Major transactions during the season

6/28/96 Signed Doug Jones as a free agent.

7/31/96 Traded a player to be named later and Greg Vaughn to the San Diego Padres. Received Bryce Florie, Marc Newfield, and Ron Villone. The Milwaukee Brewers sent Gerald Parent (minors) (September 16, 1996) to the San Diego Padres to complete the trade.

8/23/96 Traded a player to be named later, Pat Listach, and Graeme Lloyd to the New York Yankees. Received Bob Wickman and Gerald Williams. The Milwaukee Brewers sent Ricky Bones (August 29, 1996) to the New York Yankees to complete the trade. Pat Listach returned to original teams on October 2, 1996.

Well, at least the Crew got Wickman that year.

2005 (81-81)

Major transactions during the season

7/10/05 Traded Junior Spivey to the Washington Nationals. Received Tomokazu Ohka.

They also released Ricky Bottalico on 7/27/05 after Ned Yost used up everything Bottalico had left by June