The Cleveland Cavaliers announced Wednesday that John Beilein has officially resigned as head coach and will be reassigned to a different role in the organization.

"Over these last nine months, I have given my all to this organization, but after much reflection, I have decided that it is best that I step back and resign from my position as head coach of the Cleveland Cavaliers and assist the organization in a different capacity," Beilein said in a statement. "I am very grateful to [owner] Dan Gilbert, [general manager] Koby Altman and the entire Cavaliers organization for the opportunity they have provided me.

"This was a very difficult decision for me, but I want to be clear -- this was my decision to step down and I truly appreciate the understanding and support of the front office during this time. I find losing very challenging and this year has taken a much bigger toll on me than I expected. I grew concerned for the consequences this toll could potentially take on my own health and my family's well-being down the road. I was not certain I could be at my best for the remainder of the season and in the future. That would not be fair to the players, coaches and support staff."

Associate head coach J.B. Bickerstaff will take over for Beilein and was expected to run his first practice with the team Wednesday night.

"I also would not be doing this now, during the season, if J.B. Bickerstaff was not ready and capable to assume the head-coaching role immediately and continue the rebuilding process that we have started," Beilein said. "For 45 years and more than 1,300 games, my journey as a basketball coach has been a dream come true. I have never been afraid of a challenge and have given each one my all -- sometimes to the detriment of my own well-being."

Bickerstaff was hired as part of an eventual succession plan with Beilein, but that elevation came much sooner than expected after Beilein was hired in the spring.

"This gives you an opportunity to make very difficult decisions without that same amount of weight that you have to face, where as an interim you're fighting for your life," Bickerstaff said Wednesday. "This gives you a little bit of relief from that, and you can make harder decisions based on the long term and not just the short term.''

Before the Cavaliers officially announced his resignation, Beilein spoke to his players. Cleveland forward Kevin Love described the coach's actions as "ballsy'' and the mood as "powerful."

"For him to come in and do that and look us all in the eye, and acknowledge that integrity and willingness, that's big,'' Love said. "That's real man s--- right there. So I respect him for coming in and doing that because he didn't have to.''

Beilein and the Cavaliers negotiated a financial settlement that will pay him a portion of the remaining money on his 2019-20 contract, league sources previously told ESPN's Adrian Wojnarowski. Beilein left Michigan in May and signed a five-year contract with Cleveland that included a team option for the final season, a deal that paid him more than $4 million per season, league sources said.

"While it's unexpected, we understand and respect his decision to step down as head coach of the Cavaliers," Altman said in a statement. "I was excited about the development of our young players, who have all shown growth and maturity under Coach Beilein. ... The NBA is a unique business that sometimes requires aggressive risk-taking on important long-term decisions to move a franchise forward and ultimately compete for championships."

Beilein, 67, struggled to connect with NBA players and was never able to implement his collegiate offense into the pro game. The plight of some previous coaches who made the leap to the NBA also befell Beilein: players quickly tuning him out with his penchant for screaming, and believing that Beilein was treating them as young, college athletes, not as professionals, league sources previously told Wojnarowski.

Beilein also had to apologize to his players after a January team meeting in which he referred to his players as "no longer playing as a bunch of thugs," saying he had meant to use the word "slugs."

What also really hurt Beilein was the losing after so much success in college.

Cleveland's 14-40 record is the worst in the Eastern Conference and second-worst in the NBA, ahead of only the Golden State Warriors (12-43). Management expected the team to lose a significant number of games as it turned toward rebuilding its roster around a younger core, but Beilein had several missteps along the way that shook the players' confidence in his leadership, league sources said.

"He came in every day, he busted his ass, wanted to be better, wanted to change the culture,'' Love said. "But sometimes, what do they say, 'If you want to make God laugh, tell him your plans.' Sometimes it doesn't always shake out or work the way you want it to.''

ESPN's Brian Windhorst and The Associated Press contributed to this report.