The cornerback spent four years at Pittsburgh Steelers and impressed during his time at Heinz Field so much that the Saints were willing to spend big to secure his signature.
"I'm so excited about Keenan Lewis — everything about him since the day we signed him," Ryan told the Times-Picayune.
"He's got so much ability. The sky is the limit for this guy. He's going to be fantastic for us. We're so excited about him.
"He's smart, he's tough, he's long. And he's a local hero. You've got to love this guy. In my opinion, I honestly feel we got the best free agent out there on defense."
The 27-year-old has made one interception and 29 pass deflections since arriving in the NFL in 2009.