At the end, it was pretty obvious he wasn't.
Johnson lost his job Wednesday, a move the team referred to as "relieving him of his duties." The softer tone made sense considering that in three-plus seasons Johnson guided the Mavericks to the NBA Finals for the first time and to a club-record 67 wins the following season.
Yet for all the high points, there were some serious lows -- blowing a 2-0 lead in those Finals, getting dumped in the first round of the playoffs after that 67-win season and then, the final straw, getting knocked out in the first round again this season after Dallas shook up its roster and mortgaged some of its future to acquire Jason Kidd.
Over those three straight postseason wipeouts, the Mavericks lost 12 of 15 games, including all nine on the road.
"Was it time for a change? I guess," said Dirk Nowitzki, who became the league MVP under Johnson's watch. "I think this franchise, we owe him a lot. Unfortunately it's just one of those situations where everybody's got to move on."
ESPN.com's Marc Stein first reported the news of Johnson's ouster.
NBA front-office sources told ESPN.com that both the Mavs and Johnson wanted to come to a resolution quickly so Dallas could begin interviewing other candidates and Johnson could pursue another job.
The final mark during Johnson's tenure: 194-70 in the regular season, 23-24 in the playoffs.
"More than anything, I'm very grateful and excited about the opportunity to coach the Mavericks for the last three-and-a-half years, including my assistant coach stint," Johnson told 103.3 FM ESPN in Dallas.
Johnson got the news during a meeting at his condominium Wednesday morning. Donnie Nelson, the team's president of basketball operations, was there, while team owner Mark Cuban joined via cell phone from Chicago.
Johnson flew to Houston soon after because his son had an accident at school. He will meet with reporters Thursday, but called in to the local ESPN affiliate, KESN, to talk about his dismissal.
"This is something that needed to happen," Johnson said. "There's no animosity or bitterness. We all still really care about each other, but it was time to go in a different direction. We didn't win the championship, but if you look at the whole body of work that we put together over the last three-and-a-half years we'll put it up against anybody."
What will Cuban do?
It's hard to guess because he's never really hired anyone, inheriting Don Nelson when he bought the team and then agreeing with Nelson to groom Johnson.
Paul Westphal was on Johnson's staff and Del Harris remains on the payroll as a consultant. Jeff Van Gundy and Rick Carlisle are other experienced coaches who could be interested, if Cuban is. Phoenix's Mike D'Antoni also would be an intriguing option if he loses his job.
Whoever takes over will get a roster of expensive, aging players. The Mavs need to get younger and more athletic, but don't have a first-round pick or much room under the salary cap.
But Dallas does have two commodities that any coach would love to have: Nowitzki and Kidd.
While Nowitzki turns 30 this summer and Kidd just turned 35, both are coming off All-Star seasons. Kidd has a player option for next season, but it's for $21 million, more than he'd get on the open market.
"It's not at the point of pulling the plug on this," Kidd said. "I think we have a chance to be very successful, so I look forward to the challenge next year."
Cuban certainly will ask all candidates how they will get the most out of Kidd, something Johnson struggled to do.
The Mavs were 35-18 before giving up young point guard Devin Harris and a package of players and picks for Kidd. They went 16-13 after he arrived -- 17-17 counting the playoffs.
"We probably could have opened it up a little more, have a little more free flow, let Jason create and not just make him a weakside spot-up shooter," Nowitzki said. "But, you know, Avery had us believing in the system, and that's the way he thought we could be the most efficient."
Nowitzki hopes the next coach retains at least some of Johnson's emphasis on defense.
"You don't basically want to go back to the Nellie days where we just run and gun and have fun, and you get scored on every time down," Nowitzki said.
Nelson turned the Mavericks from lottery regulars to playoff regulars, then to title contenders. He just couldn't get them to the Finals.
A championship-winning point guard for San Antonio during his long career, Johnson became Dallas' coach-in-waiting in 2004-05. His wait ended just a few months later. He finished that regular season 16-2, then won his first playoff series. Then, in his first full season in charge, the Mavericks reached the NBA Finals and Johnson was named coach of the year.
When the Heat won four straight after losing the first two, there was talk of Pat Riley outcoaching Johnson and of Johnson panicking during the series by switching hotels in Miami. More talk of getting outcoached came up after the 67-win season went down in flames to, of all people, Nelson.
The knock this time was mostly over his use of Kidd. He and Cuban even had a shouting match in the coach's office following a home loss to the Lakers.
Johnson's rift with his club was apparent during the five-game series against the New Orleans Hornets.
Down 2-0, he said to blame him, but his remarks came off as sarcastic because he added it was his fault the players were missing layups, free throws and defensive assignments. Then, after losing Game 4, Johnson canceled an off-day practice, but the players went through a workout anyway -- without the coaches.
Now, those players will be answering to a new coach.
"We're just at a stumbling block, at a standstill," Jason Terry said. "I guess management's going to take a look at us and see what pieces we need and see where we go from here. You know they're going to make some moves, there's no doubt. But the backcourt looks solid and you've got the big German. That's not a bad place to start."
Marc Stein is a senior NBA writer for ESPN.com. Information from The Associated Press was used in this report.