After considering a number of candidates from outside the club, New York Giants head coach Jim Fassel has decided to stay in-house for a successor to defensive coordinator John Fox, and on Thursday promoted veteran secondary coach Johnnie Lynn to the post.

Lynn, 45, has been the team's secondary coach the last five seasons and had the support of many of the Giants' key defensive players.

Lynn plans to make subtle changes to the defense to avoid the breakdowns that led to big plays by opponents last season. New York allowed 24 passes of 30 yards or more, including seven for touchdowns.

"We're not going to do everything we did last year -- we are going to do a lot of them and we are just going to do them better," Lynn said. "We are going to fly to the ball, tackle that ball, cause takeaways and give our offense a short field."

Fassel interviewed at least two other candidates, veteran coordinators Wade Phillips and Vince Tobin, before settling on Lynn. The Giants made a contract offer to Phillips, who subsequently signed a three-year contract with the Atlanta Falcons, a deal that makes him the NFL's highest paid assistant coach.

Fox departed, of course, to become the Carolina Panthers head coach.

In the days after Fox's departure, Lynn was identified as a leading candidate for the job, but Fassel said he wanted to be diligent in researching other options. The search, he said, just kept bringing him back to Lynn, a former NFL defensive back.

"I have a lot of confidence in Johnnie," said Fassel in a statement. "He's done a tremendous job since he's been here and he's ready to take the next step. I've watched Johnnie work hard for five years. He's a bright coach, he's very energetic, very loyal and hard-working. I've seen him grow as a coach. I look at his organization, I looking at his teaching, his knowledge of the game, his interaction with people, all those criteria that make you a leader and a communicator."

For eight seasons, 1979-86, Lynn was a standout cornerback and safety for the New York Jets. A former UCLA standout and the Jets' fourth-round draft choice in 1979, Lynn finished his playing career with 17 interceptions.

He began his coaching career at Arizona in 1988 and stayed there six seasons. Lynn then joined the Tampa Bay Bucs staff in 1994, moved to the San Francisco 49ers in 1996 and to the Giants a year later on Fassel's first staff.

The Giants ranked 14th in the league on defense last season, giving up an average of 310.9 yards. They were eighth against the rush (96.6 yards) and 21st against the pass (214.4 yards).

In Lynn's first season with the Giants in 1997, the secondary led the NFL with 27 interceptions.

To replace Lynn, the Giants hired DeWayne Walker as their new secondary coach on Friday.

The 41-year-old Walker spent last season as the defensive backfield coach and associate head coach at Southern California.

He spent three seasons as a defensive assistant with the New England Patriots, and a decade in coaching jobs at several colleges, including Brigham Young and Oklahoma State.

Len Pasquarelli is a senior writer for ESPN.com. Information from The Associated Press was used in this report.