METAIRIE — The best-case scenario for the first round of the NFL draft Thursday night, as far as the New Orleans Saints were concerned, was to have one of a handful of the top-rated defensive players slide toward the middle of the round.

So when the Saints went on the clock with the 15th pick, they were looking for some immediate help, which they think they got when they chose Texas free safety Kenny Vaccaro.

After a difficult 2012 season in which his team gave up yards and points at a record-setting rate, Saints coach Sean Payton scrapped the old 4-3 defense and hired defensive coordinator Rob Ryan to put in a 3-4 alignment.

As a result, the Saints needed playmakers on that side of the ball and picked up a couple in free agency when they signed cornerback Keenan Lewis and outside linebacker Victor Butler.

In choosing the 6-foot, 214-pound Vaccaro, the Saints made a move to add another player to help shore up a defense that set an NFL single-season record in allowing 7,042 total yards in 2012.

While Vaccaro, Georgia outside linebacker Jarvis Jones and Florida defensive tackle Sharrif Floyd were available when the Saints went on the clock, Payton and General Manager Mickey Loomis looked to the secondary.

After two of the top defensive tackles in the draft — Missouri’s Sheldon Richardson and Utah’s Star Lotulelei— went back-to-back with the two picks before, the Saints selected the hard-hitting and versatile Vaccaro.

The New York Jets chose Richardson and the Carolina Panthers went for Lotulelei, leaving Vaccaro and another player Payton declined to identify in the bullpen, according to the various scenarios they had mapped out.

“I’m excited to come down there and play,” Vaccaro said in a teleconference. “That was my last visit, actually, and I had a good feeling walking out of there that it might be the Saints. So I’m excited to get down there and play some football.”

At Texas, Vaccaro started 15 games at strong safety and 13 games at free safety as well as three at strongside linebacker and one at middle linebacker.

“He’s got versatility,” Payton said. “I think when you watch him play and study game tape, he plays a lot of nickel because of the amount of spread offenses they saw in their league last year. So there were a lot of snaps where he’s playing down in the paint with two safeties behind him.”

That ability to do more than one thing is what made him attractive to the Saints.

“I think I’m real versatile and can do a lot of different things,” Vaccaro said. “I don’t have any limitations. I can cover and run-support, so I can bring that to the team.”

A defensive tackle could have helped the Saints after they finished last among the 32 teams in rushing defense, giving up 147.6 yards per game. They also ranked 31st against the pass at 292.6 yards a game.

Vaccaro, who started 32 of 51 games at Texas, had five interceptions and forced four fumbles. He and Payton said the fact that he played all over the field probably limited the number of interceptions.

He became a full-time starter in 2011 and was third in the voting for Big 12 Defensive Player of the Year by league coaches. As a senior in 2012, he earned All-America honors while leading the Longhorns with 107 tackles.

Payton said the Saints will give Vaccaro a chance to compete with starting free safety Malcolm Jenkins and starting strong safety Roman Harper for playing time.

“He can handle either safety position or the nickel,” Payton said. “We’ll just see how it goes when he comes in. We say the same thing every year: We want to create competition with everyone in minicamp and training camp.

“I felt like if he was available, we would be getting an awfully good defensive player to help our team. I think he’s got that toughness and that suddenness you like at that position.”