by Steve Kyler, Hoopsworld.com

There is an expression in the coaching world that all coaches accept and embrace: “Coaches are hired to be fired.”

Anyone who accepts a head coaching job in the NBA knows that the clock starts the moment they hold their press conference, and the easiest change a team can make is at head coach.

As the 2012-13 NBA season gets underway with training camps in roughly two weeks, there are a few coaches who have to get things going or they could very easily be out before the season ends.

Here are some of the names to watch:

Avery Johnson, Brooklyn Nets

No one expected Johnson to win games last season in New Jersey. The roster was not constructed to win games and Johnson, for the most part, got a free pass as the team prepared for this offseason. All of that changes when the Nets open their inaugural season in Brooklyn in two weeks. Not only do the Nets expect to compete, they expect to win a lot of games, and if Johnson cannot deliver a winner in Brooklyn, he could very easily be out. The saving grace for Johnson is that owner Mikhail Prokhorov likes him a great deal. However, with so much of the Nets’ future riding on them being good from day one, the expectations on Johnson have more than doubled, and if he does not deliver, someone else could be running things in year two in Brooklyn.

Lawrence Frank, Detroit Pistons

The Pistons have never been very good at hiring coaches. The Pistons have had four coaches in the seven years since Larry Brown left the team. Since then, the team has gone backward virtually every year. Frank is an excellent coach. However, if the Pistons don’t start showing serious improvement, new ownership’s patience with the process won’t last long. Team President Joe Dumars is already on the hot seat, and if Dumars goes after another ho-hum season, Frank could go with him. No one expects the Pistons to win a championship, but if the team doesn’t show serious improvement, change across the board is inevitable.

Mark Jackson, Golden State Warriors

The Golden State … [For more on NBA coaches on the hot seat, click here.]