HOUSTON — David Culley spent 43 years as a college and NFL assistant before finally getting his first head coaching job with the Houston Texans.

He lasted just one season before being fired Thursday, a move that leaves the NFL with one Black head coach: Pittsburgh’s Mike Tomlin. Miami’s Brian Flores was fired this week after leading his team to a 9-8 record.

The Texans announced the firings of Culley and offensive coordinator Tim Kelly on Thursday night. General manager Nick Caserio saying he met with both men earlier in the day to inform them of what he called a “difficult but necessary decision.”

“While a change after one season is unusual, we had philosophical differences over the long-term direction and vision for our program moving forward,” Caserio said in a statement. “We appreciate coach Culley for helping us navigate through a difficult season, but it is my responsibility to make decisions that I feel are best for our organization.”

Houston finished 4-13 this season, concluding with a 28-25 loss to Tennessee, the AFC’s top playoff seed.

Culley said Monday he expected to return, but Caserio was said to still be evaluating the coach at that time. Three days later, Culley was out of a job.

“I loved every minute of being the head coach of the Houston Texans,” Culley said in a statement. “I appreciate the players and coaches for staying the course with me through the ups and downs of our season. I’m disappointed we didn’t win more games and I won’t have a chance to improve on the lessons I’ve learned, but I fully understand this is a bottom-line business and I didn’t do enough.”