Underhill: Elite secondaries power Super Bowl teams, and constructing just such a unit is a key task for the Saints _lowres

Advocate file photo by MATTHEW HINTON -- New Orleans Saints cornerback Keenan Lewis

PHOENIX — Run you finger down the Super Bowl rosters and take a look at the names.

The Bradys, Lynchs, Gronks and Wilsons populating each team will immediately pop out. But there’s a common thread between both of these teams: Their secondaries are among the best in the NFL.

We’re all familiar with Seattle’s Legion of Boom, made up of Richard Sherman, Earl Thomas, Byron Maxwell and Kam Chancellor, who Sherman once said “takes people’s souls.” New England’s group of Devin McCoury, Darrelle Revis, Patrick Chung and Brandon Browner lacks a catchy nickname, but they might be every bit as good as the LOB.

These are elite units and both teams have invested heavily in these positions. And in a league where 15 teams passed on 60 percent of their offensive plays during the regular season, this is undoubtedly a prudent approach to roster building.

It would be inaccurate to say the Saints are unaware of this trend or went cheap with their secondary. This team is fully aware of how critical the safety and cornerback positions are. It dropped $56 million on Jairus Byrd last season thinking he was the difference between good and great.

He wasn’t — at least not immediately. Byrd struggled early in the season and then finished the year on injured reserve. It was a miss no one saw coming. The guy the team really missed on was cornerback Champ Bailey, who was dead on arrival and left the No. 2 cornerback spot barren.

How and why this team thought Bailey could be the guy is a mystery. Those in Denver knew he was finished last year. The only plausible explanation is that New Orleans was fooled by his name. In a blind taste test, there’s no question the Saints would have properly identified Bailey as a can of RC Cola and not Coke. It happens.

But if one needed reminding just how important it is to have a functioning, elite secondary, this Super Bowl will hammer the point home.

If the Saints are to put this futile season behind them and quickly rebound in 2015, then they are going to finish last year’s job and solidify the secondary.

This might be a situation where you’re sitting on a beach and looking at a peninsula across the way and go, “Yeah, I could swim that,” when in reality it’s more than a mile away. But right now, with the seasons months away, it really doesn’t look that hard to get across the water.

Three of the four pieces are already in place.

There’s no way Byrd is suddenly as bad as he looked during the first six weeks of the season. Byrd will have the offseason to get familiar with the defense and will be a year removed from the back surgery that kept him sidelined early in camp.

And we know how talented Kenny Vaccaro is at strong safety. He can make things happen. But, as he admitted last season after being moved from strong safety, he needs to eliminate the negatives by staying within the framework of the defense and not trying to force things. This can be done.

The one cornerback spot is already locked down by Keenan Lewis. All this secondary really needs is another cornerback who goes down smoother than a can of Faygo. There are some internal options like Delvin Breaux, and if somehow he goes through a rapid development this offseason, perhaps last year’s second-round pick, Stanley Jean-Baptiste.

But neither of those players can be counted upon to contribute anything entering the offseason. Someone needs to be brought in from the outside. If one of the other guys rises up and knocks him off, that’s fine. But he’ll need to earn it.

And by brought in, that means the Saints need to sign a veteran player who is a proven commodity. Next year can’t be the same as last year. No gambles, no guessing. Sure things only.

A viable, consistent pass rush would also help, but that’s a story for a different day.

It’s entirely possible this optimism drowns in the water once camp opens and we get a look at these players. But there’s enough there that, with a little tweaking, it could all come together.

It has to. It’s the only way this defense can start destroying souls and get back in the Super Bowl hunt.