When Texans head coach Bill O’Brien elected to name Brian Hoyer as his team’s starting quarterback, he did so with a caveat.

“If things aren’t going well, look, we’re not on a short leash,” O’Brien said to both Hoyer and backup Ryan Mallett when alerting them of his decision on HBO”s Hard Knocks. “But, we’re not gonna like, sit there, and let it go like eight games of not being very good.”

Then he delivered a message to Mallett, his newly demoted signal caller.

“You need to be really, ready to go.”

During the Texans 27-20 loss to the Kansas City Chiefs Sunday at NRG Stadium, Hoyer’s leash was gone before the game even ended. The Texans coach explained why he lifted Hoyer in favor of Mallett.

“I felt like it was the best decision for the team.”

Mallett took the reins of the Texans offense with 6:10 left in the game, trailing 27-9. He completed 4-of-5 passes for 42 yards on the Texans’ 6-play, 59-yard scoring drive, capped by De’Andre Hopkins’ second touchdown catch of the day, and drove the team 48-yards in 10-plays on the team’s next drive resulting in a Randy Bullock field goal.

“At the end there, we started moving it, but it was way too late,” O’Brien said.

Mallett finished 8-of-13 for 98 yards and a touchdown leading as many scoring in two possessions as Hoyer did in 12, but when asked who is starting quarterback would be next week in Carolina, O’Brien didn’t have an answer.

“I don’t know, Brian,” O’Brien snapped at Chronicle columnist Brian T. Smith. “I just walked in here. I just got in off the field. No idea. We’ll review the film and we’ll find out once we head into next week.”

In his Texans debut, Hoyer completed just over half of his 34 attempts (18) for 236 yards and a touchdown, but committed two turnovers inside the Texans 20-yard line, helping Kansas City score 14 points, but when asked if his opinion of his two quarterback’s had changed after Sunday’s loss, O’Brien wouldn’t say, repeating an earlier line.

“I don’t know yet.”

“I’ll go in there and watch the tape and make an honest evaluation and make a decision one way or the other going into the Carolina game.

[twitter-follow screen_name=’AdamSpolane’]