A week after struggling in Houston's blowout loss to the Miami Dolphins, safety Rahim Moore was a healthy scratch for the Texans.
Andre Hal started at free safety in place of Moore in Sunday's 20-6 win over the Tennessee Titans, opposite Quintin Demps.
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"With this game, we felt like that was the best combination of safeties," O'Brien said, per the Houston Chronicle. "That's what we were doing."
Moore signed a 3-year, $12-million deal with the Texans as a free agent last March.
Hal finished the game with two tackles, but contributed to a defensive effort that limited the Titans to a pair of field goals.