Petrino filled the final vacancy on his coaching staff Wednesday when he announced that former St. Louis Rams secondary coach Willy Robinson has been hired as Arkansas' defensive coordinator.
Robinson's hire ends a secretive search by Petrino to find a replacement for Ellis Johnson, who resigned as Arkansas' defensive coordinator on Jan. 24 to accept the same position at South Carolina.
Robinson, who turns 52 on Sunday, will also serve as the Razorbacks' safeties coach.
"Coach Petrino and I have spent a couple of days together, and the thing about that is he came away feeling comfortable with the fact that we had the same philosophy and share the same philosophies," Robinson said during Arkansas' National Signing Day news conference.
Johnson said he was excited to return to the college ranks after spending the past seven years working for NFL teams, including the Rams, New Orleans Saints and Pittsburgh Steelers. He was the San Francisco 49ers' defensive coordinator in 2004.
Petrino said he heard recently from a mutual friend that Robinson was interested in filling Arkansas' vacancy at defensive coordinator.
Petrino interviewed Robinson in St. Louis, then met with several other candidates before finally offering him the job.
"Well, I've known Willy for a long time," Petrino said. "In fact, when I got the (head coaching) job with (the) Atlanta (Falcons), I tried to get a hold of Willy and see about bringing him down there as my coordinator."
Petrino was very tight-lipped during his two-week search to replace Johnson, though Alabama defensive coordinator Kevin Steele was reportedly approached about his interest in the job.
Johnson's resignation after only three weeks at Arkansas didn't come as a total surprise. He spoke during his introductory news conference on Jan. 9 about his desire to get back to South Carolina, where he grew up.
But Robinson's hire puts an end to a rather awkward time for Petrino's other assistants, who continued recruiting even though they didn't know who their defensive coordinator would be.
"Well, there is no uncertainty because you know it (hiring a defensive coordinator) has to happen," Arkansas secondary coach Lorenzo Ward said. "The uncertainty is who is that (individual) going to be and what their philosophies are going to be."
Robinson said his defensive philosophy is rather simple: It's all about being fundamentally sound.
"If you don't start there with simplicity and fundamentals and discipline, regardless of what else you come up with, it's a crapshoot," said Robinson, whose last job was as the Rams' secondary coach in 2006-07. "So that's where our philosophy starts."
It's uncertain how much Robinson will be paid by Arkansas.
Johnson had agreed to a three-year deal worth $350,000 annually, the same amount former Arkansas defensive coordinator Reggie Herring received last season.
But Arkansas officials didn't release the details of Robinson's financial agreement on Wednesday.
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