X factor: Jabari Greer, Saints CB

New Orleans cornerback Jabari Greer. He could turn out to be the most important player on the field Saturday, despite having barely played in the second half of the regular season.

Greer missed seven weeks with a groin injury and returned to get a little tune-up in the regular-season finale against Carolina. But you can pretty much trace the overall decline in New Orleans’ defensive play to when Greer went down. Fellow starting cornerback Tracy Porter also was injured for much of the same time Greer was, and a secondary that was excellent for the first half of the season became very ordinary.

The Saints were forced to play rookie Malcolm Jenkins and briefly brought in veterans Mike McKenzie and Chris McAlister. That brought a change in style and attitude to the secondary. Free safety Darren Sharper, who was an interception machine early in the year, suddenly had to play more of a Cover 2 scheme to help the cornerbacks.

But Porter has been back for several weeks now, and all indications are that Greer should be at full health. That will allow Sharper to go back to being a center fielder, and that makes this defense a lot more dangerous.

Greer, a former college track champion, brings great speed, and that’s going to be necessary against an Arizona receiving corps that’s one of the best in the league. Greer may give up some size to Arizona’s top receiver, Larry Fitzgerald, but he has the speed and athleticism to at least stay close to him.

Arizona has plenty of other weapons, but having Greer back means the New Orleans secondary is suddenly much better equipped to deal with that. Jenkins or veteran Randall Gay will be on the field a lot as the nickelback. But Jenkins and Gay are more competent in that role than they were when they were being asked to be No. 1 cornerbacks.

Having Greer back might not correct every problem, but it should put this defense a lot closer to what it was early in the season.