HOUSTON --More than 30 Houston Texans have shown up at Reliant Stadium and immediately started conditioning drills and meeting with their coaches. The Texans open training camp on Sunday, 15 days ahead of their preseason opener against the New York Jets on Aug. 15. Houston's pass defense ranked as the league's worst in 2010. New coordinator Wade Phillips met with his players Tuesday to begin teaching them the 3-4 defensive alignment, a switch from last year's 4-3. The Texans are expected to be active players in free agency, possibly making a bid to sign All-Pro cornerback Nnamdi Asomugha. Houston also wants to re-sign All-Pro fullback Vonta Leach. Ralph Vitolo, Leach's agent, says the Texans have contacted him.