Team president Michael Bidwill shakes the hand of Tyrann Mathieu after Mathieu signed his first NFL contract Thursday.

Tyrann Mathieu may be a work in progress in settling into NFL life, but it still didn't take long to officially get him started.

The Cardinals' third-round draft pick signed his initial contract Thursday, a four-year deal that was done in relatively quick fashion.

"I never doubted it," Mathieu said of getting the chance to sign an NFL contract. "I knew it was a long shot and it would be a process, but to finally sit down and sign my name on the dotted line means a lot to me."

Full terms of the contract were not available – including what Mathieu and the team agreed upon in the quest to keep Mathieu away from any further issues with any illegal substances – but

Mathieu had said previously he was ready to work with the team to make sure that happened.

"Not that difficult," Mathieu said with a smile. "It was kind of a walk in the park."

(UPDATE: The Cardinals moved two-thirds of Mathieu's signing bonus into roster bonuses to protect themselves should Mathieu relapse. For the full details, click here.)

Mathieu becomes the sixth of nine draft picks to sign. The only players left to get their contracts are first-round pick Jonathan Cooper and fourth-round picks Alex Okafor and Earl Watford.

The new collective bargaining agreement has changed the time frame in which deals get done. Prior to 2011, rookie contracts were often worked on in July, and most years the first-round pick's deal got pushed into the start of training camp.

Now, however, all rookie deals are slotted, making true negotiations a thing of the past. Even with a player like Mathieu, who had other issues at play that needed to be factored in, signed quickly. Last year, the Cardinals had all of their draft picks under contract by June 11.

"I'm part of a family now, so I'm obligated to the community and the entire Arizona Cardinals organization," Mathieu said. "The Bidwill family, Steve Keim, the coaching staff, I'm obligated to everybody now. It's my responsibility."