"I feel just like I have something to prove to myself," Walker said in a conference call with South Florida media. "They know what type of player I am. I have nothing to prove that I haven't shown them before."
Walker wound up leaving the Dolphins as an unrestricted free agent in the offseason after the team made it clear they could only re-sign one of their two starters at safety, Walker or Brock Marion.
Ironically, both Walker and Marion talked to the Lions before Marion decided to re-sign with Miami.
"I love Brian, he knows that," said Coach Dave Wannstedt. "But with the way the system is nowadays, we could only keep one. The guys knew up front we wanted one of the two back. Brock was the senior leader, so we gave him the first preference and he wanted to come back."
Walker, for his part, said he didn't get the kind of offer he wanted from the Dolphins, saying, "If they really wanted me, I'd still be there."
But that's in the past now, and Walker is busy trying to help the Lions improve from last year's 2-14 disaster.
And so far he has made his new team happy about its offseason acquisition.
"He's a heck of a football player," said Coach Marty Mornhinweg. "He's playing lights out. I know he'll want to win this game. I would expect him to play very well."
As far as Walker being able to share Dolphins secrets with his new team, he could tell the Lions some things about the Miami defensive scheme but any tidbits he could share on the Miami offense probably is obsolete because of the new system installed by Norv Turner.
Said Dolphins quarterback Jay Fiedler: "He hasn't seen us run this offense in practice. There will be a lot of different reads for him. There is some familiarity. As much as he might know about us, we know about him, too. I think that offsets any advantage."