In his first stint in Cleveland he went to playoffs every year, he took Lebron and some dudes from the club to the NBA Finals in his second year, won 60+ games his last 2 seasons and was fired and had to go work for ESPN.
A year later he was hired by the Lakers and went to playoffs in the lockout shortened season, the next season he was fired after 5 games due to a slow start when newly acquired Steve Nash was hurt, Dwight was recovering from back surgery and Kobe was playing with an injured foot and couldn't practice.
He had a second run in Cleveland with Kyrie and some bums and had his first losing season over 82 games and was fired again a year later.
He sat at home for 2 years until he was hired to be an assistant in Golden State. When Steve Kerr was out he led the Warriors to a 12-0 post season record but got zero credit for it. Luke Walton who Brown replaced went 39-4 in the regular season when Kerr was out and continues to get job after job because of that. Meanwhile Brown's name doesn't even come up for head coaching jobs any more even though he's only 49 and his .616 winning percentage is top 10 in NBA history for people that have coached more than 3 seasons.
Won 60 games and went to the NBA Finals his first full season as head coach in Dallas, won 67 games the 2nd year but got upset in the first round because MVP Dirk bitched up. The following season won 51 games but lost in the first round to Byron Scott's Hornet's and was fired. He went to work for ESPN for 2 years and then took over a bad Nets team and was fired in his 3rd season with a .500 record just as they were starting to turn around. He went back to TV and ended coaching in college. Again his name doesn't even come up anymore for NBA head coaching jobs despite his .577 career winning percentage. The guy that replace him in Dallas Rick Carlisle won a title in his 3rd year but since had had 4 winning seasons in 8 years and has had a losing record the last 3 years but his job security isn't even in question.
Took over a trash Nets franchise and had them in the NBA Finals in his 2nd and 3rd year. Was fired midway through the 4th season with a winning record. Took over a trash New Orleans franchise, had them in the playoffs his 4th & 5th seasons yet was fired 9 games into the 6th season. Took over a trash Cleveland team after Lebron left the first time and was fired after 3 seasons before he was able to turn them around... https://www.cleveland.com/cavs/2013/04/cleveland_cavaliers_players_st.html Took over a trash Laker team in Kobe's final 2 years while trying to develop younger players but was again fired before he was able to finish the job. He's now doing tv because he is not even on the NBA coaching radar...
Took over a trash Warriors franchise and had them in the playoffs in years 2 and 3 and them was fired so Steve Kerr could reap the benefits of the players Mark Jackson developed. Now he's doing tv and barely gets a whiff for other NBA head coaching jobs despite a .526 winning percentage.
Meanwhile these trash ass white coaches lose and walk right into another head coaching job, they don't have to go back to being assistants or doing tv work...
Luke Walton: https://www.basketball-reference.com/coaches/waltolu01c.html Rode Steve Kerr's coattails off the player's Mark Jackson developed, didn't do shit in his first head coaching job with the Lakers, after they "agreed to part ways" he was promptly given another head coaching job in Sacramento despite a .398 winning percentage.
Mike D'Antoni: https://www.basketball-reference.com/coaches/dantomi01c.html Got his first head coaching job with Phoenix and had some success but couldn't get them past the conference finals so he left there and went to the Knicks where he was mostly trash but still given the Lakers head coaching job and he ran them into the ground. He was an assistant in Philly for a year then was given the Houston job and is still trying to get them to the Finals.
A Greg Popovich disciple that had some early success with his first head coaching job in Atlanta but the wheels fell off quickly. Eventually he and the Hawks "agreed to part ways" because white coaches rarely get fired they just decide to leave. He was given the Bucks job and is reaping the benefits of players developed by Jason Kidd.
Another Pop disciple, had 4 terrible seasons in Philly during "the process" but some of the young players he had eventually developed and they had some success the last 2 years but his teams have looked shaky in the playoffs but the players need to figure it out because white coaches are never blamed for their teams struggles.
Took over and Memphis team that had fired Lionel Hollins after a 56 win season and a trip to the conference finals. Joeger never got anywhere close to that and lost in the first round 2 out of 3 years. Was fired but was promptly given another head coaching job in Sacremento where despite some young talent he wasn't able to finish over .500 in 3 seasons and was fired again but I wouldn't be surprised if he gets another head coaching job next season.
We'll see, somehow as an assistant under Dwane Casey, Nurse was credited with everything right with the Raptors while everything that went wrong with the Raptors was blamed on Casey who was fired. Nurse won 58 games, 1 less than the 59 Casey won in his last year we'll see how far they get in the playoffs with the addition of Kawhi Leonard.
These are just a few of the obvious examples, there are a lot more that have been more subtle...