While several potential free-agent cornerbacks, including Johnathan Joseph, Carlos Rogers and Ike Taylor, could help improve the Texans' league-worst pass defense from a season ago, the options at safety appear to be less attractive. If Houston can't find the versatile safety it covets, we hear there are at least two in-house candidates who could vie for a starting job alongside CB-turned-safety Glover Quin. Heading the list is third-year player Troy Nolan, who tied for the team lead in interceptions (three) last season. Another player we've been told to keep an eye on is Dominique Barber. Although Barber has wound up on injured reserve each of the past two seasons and has a limited ceiling, he figures to at least get a look when training camp eventually opens. Rookie Shiloh Keo, who, along with Nolan is more of a box safety, also could be in the mix, although he figures to make his biggest initial impact on special teams.