Houston Texans defensive coordinator Romeo Crennel, left, and head coach Bill O'Brien laugh as they watch the beginning of a joint NFL football practice between the Texans and the San Francisco 49ers at the Methodist Training Center in Houston, Thursday, Aug. 16, 2018. (Brett Coomer/Houston Chronicle via AP)

Bill O’Brien is out as the Texans head coach and general manager.

Veteran defensive coordinator Romeo Crennel is in for the remainder of the season.

The move was made Monday when O’Brien was suddenly fired after seven seasons. In a season of great expectations, the Texans have gotten off to a disappointing 0-4 start.

“On behalf of my family and our entire organization, I want to sincerely thank Bill O’Brien and his family for their impact on our franchise,” Texans CEO Cal McNair said in a statement.

“Bill’s leadership moved our organization forward as he guided us to four AFC South division championships, 52 wins and multiple playoff appearances during his tenure. Bill proved himself as a coach and leader in this league.”

As much as the firing came down to lack of winning, O’Brien’s personnel decision making that has put the Texans in a bind may have played as big a role. The trade of star receiver DeAndre Hopkins looms large in the decision to part ways with O’Brien.

O’Brien traded Hopkins, Deshaun Watson’s primary target for three seasons, the Arizona Cardinals for running back David Johnson and a second-round draft pick. So far, Johnson is averaging just 3.86 yards per carry while Hopkins leads the NFL with 39 catches through four games.

But that isn’t the only questionable decision O’Brien made after assuming the general manager duties. He traded former first-round pick Jadeveon Clowney to Seattle in a contract dispute and then send two first-round picks and a second to Miami for left tackle Laremy Tunsil and wide receiver Kenny Stills.

So not only are the Texans clearly behind the two elite AFC teams – the Kansas City Chiefs and Baltimore Ravens – but they lack the ability to improve the team through the draft anytime soon.

O’Brien, however, defended decisions on his way out the door Monday.

“I think that every decision we made was always in the best interest of the team,” O’Brien said. “We had long conversations. We put a lot of research into them. There were things that happened within the walls of an organization that the outside public will really never know and that’s just the way it is. I totally understand that.”

O’Brien exits having won four AFC South Division titles and finishing with a 52-48 record. The team regularly made the playoffs under his watch but always underachieved once there.

That combined with the 0-4 start, which included Sunday’s home loss to previously winless Minnesota was enough.

“You’ve known me for seven years, I don’t make excuses,” O’Brien said. “We just didn’t do enough. Whatever it is. You look back on it, hindsight’s 20-20, right?”

Now the job goes to Crennel, who at 73, is the oldest coach in the NFL and one of only a handful of African-American coaches in the league this season. Crennel, who was demoted to assistant head coach from defensive coordinator this season, was the Cleveland Browns head coach from 2005-2008 and served as the Chiefs interim head coach during the 2011-2012 season.

Crennel has been with the Texans since 2014 as either the assistant head coach or defensive coordinator and sometimes held both titles simultaneously.