O'Brien has a good idea of who his starting quarterback will be for Sunday's game against the Carolina Panthers, but he isn't sharing that information.
"You'll have to wait until the first offensive play of the Carolina game to see who the quarterback will be," O'Brien said.
Hoyer completed 18-of-34 passes Sunday with one touchdown and one interception and was sacked four times. Mallett entered the game with the Texans trailing 27-9. He threw a touchdown and a two-point conversion and then led a field goal drive. The Texans could not recover an onside kick with less than two minutes remaining, which would have given them the opportunity to tie the game.
Mallett finished 8-for-13 for 98 yards and a touchdown.
O'Brien declined to evaluate each player's performance. He also declined to give the reason for benching Hoyer.
"There were other guys that we substituted for," O'Brien said. "Every decision is made in the best interest of the team that we think will ... give us the best chance to win the game."
Asked if he didn't consider the quarterback position different from other positions, O'Brien repeated his mantra.
"Again, I try to make decisions that are in the best interest of the team that point us in the direction of winning," he said.
Hoyer and Mallett both signed two-year deals with the Texans in the offseason after testing the free-agent market. Hoyer's contract is worth $10.5 million while Mallett's is worth $7 million.
Mallett spent 2014 with the Texans, beginning the season as Ryan Fitzpatrick's backup after the Texans traded for him on Aug. 31. Fitzpatrick went 4-5 in his first nine starts before the Texans replaced him with Mallett after their bye week. Mallett started two games, a win over the Cleveland Browns in his first start and a loss to the Cincinnati Bengals in the second, during which he played through a torn right pectoral muscle.
After re-signing with the Texans this offseason, Mallett challenged Hoyer for the team's starting job but lost that competition. The day after Hoyer was named the starter, Mallett said he disagreed with the decision and added that he knew he would get an opportunity to play this season.