The team made the decision to not offer him a contract or put the franchise label on him this season, making him an unrestricted free agent, able to sign with any team.
Last year, after Robinson was offered a contract for $23 million guaranteed, he turned it down, was given the franchise tag and earned nearly $10 million. He didn't report to the team until the first week of the season. Missing training camp showed and he didn't play well until the last half of the season.
The Texans are rolling the dice not bringing him back, which makes cornerback a high priority in the draft. They still have Glover Quin, Brice McCain and Jacques Reeves, but the team obviously feels the money would be better spent elsewhere.