All SPB IV - 1974 Managers,  Here is the report of players not used 50% for 1974.   
I will list by team name and manager.  Then with player name, main position, and disposition. 

Amboy Dukes (Doc Schweitzer)
Bob Barton, c *
John Boccabella, c *

Blue Ridge Mountaineers (Steve Brunner)
Tom Egan, c  (1975)
Dennis Paepke, c *
Larry Brown, inf *
Ray Busse, ss*
Dave Hilton, 3b  (1975)
Jack Heidemann, ss (1975)
Jim Howarth, of *
Steve Barber, p *

Canton Moondogs (Tom Kackley)
Jim Ray Hart, 3b *

Cleveland Spiders (Chris Williams)
Pat Bourque, 1b *
Hal Breeden, 1b (1975)
John Donaldson, 2b *
Rich Morales, 2b *
Craig Robinson, ss (1975)
 
Dayton Triangles (John Turnbull)
Ossie Blanco, 1b *
Tom Timmerman, p *

Evanston Black Sox (John Ungashick)
Orlando Cepeda, 1b *
Andy Kosco, of  *
Chris Ward, of *
Charlie Manuel, of * (1975)
Steve Arlin, p *
Barry Lersch, p *

Flushing Rats (Joe DeZarlo)
Gene Lamont, c  (1975)
Tom Lundstedt, c (1975)
Frank Tepedino, 1b (1975)
Terry Hughes, 3b *
Paul Schaal, 3b *
Barry Raziano, p *

Gonzaga G's (John Dewan)
Glenn Redmon, 2b *
Eddie Leon, inf *
Lowell Palmer, p *
Stan Thomas, p (1975)

Hollywood Stars (Don Zminda)
Mike Ryan, c *
George Culver, p *

Kenosha Eagles (Dave Lauer)
Horace Clarke, 2b *
Leo Cardenas, ss  (1975)
Matty Alou, of *
Steve Dunning, p (1976)**

Lafayette Chiefs (Steve Ehresman)
Nate Colbert, 1b (1975)
Paul Popovich, inf  (1975)
Ron Santo, 3b *
Bill Sharp, of (1975)

Las Vegas Thunder (Mike See)
Ron Hodges, c (1975)
Rob Sperring, inf (1975)
Gene Hiser, of (1975)
Jerry Cram, p (1975)
Mac Scarce, p (1975)

Rockford Forest Cities (Terry Baxter)
Chris Cannizzaro, c *
George Theodore, of *
Bobby Floyd, inf *
Mike Reinbach, of *
Bill Slayback, p *

Rossville Cubs (Rick Ryan)
Reggie Sanders, 1b *
Vicente Romo, p (1982) **

Schaumburg Saxons (Vin Onstott)
Tim Hosley, c (1975)
Tommy Harper, of (1975)
Steve Blass, p *

Spirit Mountain Volcanoes (Marc Hollingsworth)
Herb Hutson, p *
Daryl Patterson, p *
John Strohmayer, p *
Rich Troedson, p *

Terre Haute Phillies (Mike Boling)
Bill Gilbreth, p *

Twin City Replacements (Marc Robinson)
Curt Motton, of *

* player never plays in MLB again.
**  player comes back in rookie draft of year in parenthesis.

To wrap this report up, here are the four teams who did not loose anyone for being underused during 1974:

Ashville Tourists (Rich Applegate)
Fairfax Peppers (Ron Peterson)
Frankfort Tigers (Gary Plunkitt)
Niskayuna Red Storm (Don Rahn)

Overall, only a few players lost with much value left.  Pretty good job everyone!  This concludes the 50% report. 

Best,
Gary