Watson (not injury-related) has been ruled out for Sunday's game against the Bills.
Watson, who has been inactive for Houston's first three games, thus is destined for another healthy scratch Week 4. With Tyrod Taylor (hamstring) still on injured reserve, Davis Mills will serve as the team's starting quarterback versus Buffalo, while Jeff Driskel once again is in line to be elevated from the practice squad to the Texans' active roster to handle backup duties.