My coaches are 76-17, so I haven't picked too many bad ones

Nate McMillian 0-1
Jim O'Brien 1-2

Everyone else is .500 or better, including

Don Nelson 7-0
Maurice Cheeks 6-0
Greg Popovich 5-0
Flip Saunders 5-0
Jerry Sloan 4-0
Tim Floyd 3-0
Randy Ayers 2-0
Hubie Brown 1-0
Rick Carlisle 1-0
Jim O'Neill 1-0

And, honorable mention to

Rick Adelman 11-2
Phil Jackson 8-2
Jeff Van Gundy 5-1