Seventeen NBA coaches, more than half the league's 29 teams, have been replaced since the end of the 2002-03 season: Jim O'Brien, Boston Bill Cartwright, Chicago Keith Smart, Cleveland Rick Carlisle, Detroit Rudy Tomjanovich, Houston Isiah Thomas, Indiana Dennis Johnson, L.A. Clippers Pat Riley, Miami George Karl, Milwaukee Byron Scott, New Jersey Paul Silas, New Orleans Don Chaney, New York Doc Rivers, Orlando Larry Brown, Philadelphia Frank Johnson, Phoenix Lenny Wilkens, Toronto Doug Collins, Washington

Byron Scott guides the Nets to two consecutive Finals appearances. Rick Carlisle wins 50 games back-to-back with the Pistons. Isiah Thomas coaches in the All-Star Game. Doc Rivers wins Coach of the Year. Jim O'Brien makes the conference finals.

Fired. Fired. Fired. Fired. Resigned.

Has it ever been tougher to be an NBA coach?

"This is my 37th year, and I've never seen more demands and expectations on coaches," says Magic senior vice president Pat Williams. "Man, it's like we need a miracle every night. Every team has to go 82-0 or we're not happy."

O'Brien is the sixth NBA head coach replaced already this season, and the 17th since the end of the 2002-03 season (see box). Among those relieved of their duties have been some of the game's biggest names: Lenny Wilkens, George Karl, Rudy Tomjanovich, and Paul Silas. Even by pro sports standards, it's been dizzying.

Losing coaches have always been fair targets for the unemployment line. What makes this year's carousel unique is that even winning coaches like Carlisle, Thomas and now Scott have been forced to ride it. As Suns senior executive vice prs and former longtime NBA coach Cotton Fitzsimmons said: "Usually when a team is really bad, the coach gets fired. But when you see it happen to guys who have won a lot of games, it is surprising."

What is it about the NBA that makes coaches so expendable these days?

Veteran league watchers say it's a combination of factors, not the least of which involves the power of today's players. More and more, superstars call the shots. Scott's dismissal in New Jersey, for example, appears to be at least partially due to philosophical differences with star point guard Jason Kidd.

"With the salaries today, the players more than ever before have a great deal to say about it," Fitzsimmons said. "They have a direct line to the GM or owner."

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Impatient owners, fickle fans and a hypercritical media also play a role. Whereas in the past a team might be willing to stand by a struggling coach, it now faces much more pressure from the public and media to act decisively. As Nets general manager Rod Thorn admitted Monday: "Maybe there is not as much patience today as there was 10 years ago."

The NBA's collective bargaining agreement doesn't help coaches' security, either. Because trades are so hard to make, teams often have little or no way to shake up their rosters or to get rid of players who are causing problems. Firing the coach is often the only way to make a change.

The ironic thing is that turning over coaches often leads to more suffering. By going for the quick fix, teams give up the chance to develop continuity and chemistry that can become a foundation for success. As evidence, Fitzsimmons points to the success this season Jazz coach Jerry Sloan (16th season) and Timberwolves coach Flip Saunders (eighth season).

"In both of those cases, the owner or GM stands behind the coach," he said. "You don't see enough of that anymore in the NBA."

There's also an element of unfairness to giving a coach a quick hook. Although NBA coaches know it's a crazy business when they sign up, it doesn't change the fact that most pour their heart and soul into their job. "Coaching in the NBA is not easy," Williams said. "It's like a nervous breakdown with a paycheck."

The paycheck, in fact, might be the only reason not to feel sorry for them. Scott, for example, will still be paid the remainder of his $4 million salary this season. In the meantime, he can rest easy knowing that there will be a spot for him on the NBA coaching carousel someday in the near future.

Marty Burns covers pro basketball for SI.com.