NBA coaching candidates: Billups, Rajakovic, Allen and other top names league insiders are buzzing about

Who could succeed Brad Stevens as Celtics coach? (1:02)

Adrian Wojnarowski explains why the Celtics' coaching vacancy will draw heavy interest from many candidates around the NBA. (1:02)

For nine years we've been talking to former NBA head coaches, current head coaches and future head coaches about the job that just 30 people in the world occupy: How is it changing? What did you know in Season 5 that you didn't know in Season 1? What is the job fundamentally? We've asked current and former players for the qualities they most value in a head coach. We've asked front-office executives how where their team is in its life cycle dictates the profile of the coach they pursue. We've asked agents which trends they've noticed in the hiring process.

We've also identified potential prospects prior to their prime candidacies -- those whose scouting reports suggested they had a good chance of succeeding as a first-time head coach. Steve Kerr in 2013, Quin Snyder in 2014, Ty Lue and Kenny Atkinson in 2015, Nick Nurse and Stephen Silas in 2016, James Borrego and Taylor Jenkins in 2018.

The coaching market moves in cycles, with some years more active than others. Though insiders expected a quiet offseason, several openings have already become available.

In recent seasons, the NBA head-coaching position has expanded in scope, a trend that has accelerated with the emphasis on areas like sports science and quantitative analysis. There's a lot to do, and not much time to do it, particularly this past season with a packed schedule.

A head coach is now Multitasker-in-Chief -- an executive in his own right who must understand how to manage up, down and sideways. Peek inside the training facility of a team with multiple superstars, and you'll likely find an exhausted head coach in his office. Step inside the owner's suite for a losing team, and the boss might be grumbling about how the basketball genius who charmed him at dinner during the interview process is a man of only average intelligence who couldn't lead a team out of a paper bag. And coaches say the media piece is more challenging than ever in a world where everyone in the locker room and front office is running on the narrative treadmill.

As we do every year, we spoke about the state of the profession with dozens of league insiders in the months since last year's Finals. Several common themes about the nature of the gig emerged: