New Orleans Saints linebacker A.J. Klein (53) pressures Houston Texans quarterback Tom Savage (3) during the second quarter on Saturday, Aug. 26, 2017, at the Mercedes-Benz Superdome.

There used to be an easy way to move the ball on the New Orleans Saints: Just throw it into the flats, and let your speedy players run up the field.

This seems true, at least anecdotally. It was probably never that simple, but it used to feel that way, and it was a problem during the 2015 season, Rob Ryan’s last as defensive coordinator. While there were many reasons that led to him being fired midseason, his defense was gashed by the Washington Redskins on passes to the flats during his last game at the helm.

Those defenses were often disorganized — an issue cured under coordinator Dennis Allen — and sometimes lacked talent. But there was also a lack of speed, and that carried over into last season. That’s why the team made a conscious effort this offseason to locate players with more range and the ability to swarm to the ball.

“We got a little more athleticism on the field, and that’s always a good thing,” Allen said in a video posted to the team’s website. “This game has become such a wide-open, spread-out offensive game that you really need speed on the field. Your ability to play in open space is going to determine how good you are defensively.”

Safety Kenny Vaccaro is one of the longest-tenured players on a defense that has been rebuilt over the past four seasons. He was here during the highs of the 2013 season, when New Orleans had a top-ranked defense, and the lows of the past three seasons.

During the down periods, he has often cited defenses such as Seattle’s and Denver’s, which have speed all over the field. He’ll point out how they swarm to the ball and never give up easy yards. Those are the defenses that often also do a good job of creating turnovers by having good population to the ball.

“That’s all heart. There’s no stopwatch on that. You can’t measure that,” Vaccaro said. “You get a group of guys, and they come together and have one common goal. (If) you get guys who lead and demand that, then that will come. You can only ask a guy to do it so much before you weed him out and bring another player in who will do it. That’s what we’re trying to do when we build that (roster).”

That approach is something Vaccaro has wanted to see in New Orleans. There were times when it felt close. Last summer, with players like Dannell Ellerbe and Craig Robertson at linebacker, felt like a step forward, but Ellerbe couldn’t stay healthy, and the improvement never came to fruition.

“I think we’ve drafted people that want to come in and play nasty, play physical, and that leads to everyone looking faster on the field,” Vaccaro said. “Most of the time, playing faster is people playing with better effort.”

When the Saints were retooling their defense this offseason, one of the things the team keyed on was improving at linebacker. Specifically, the team knew it had to get more athletic. New Orleans signed A.J. Klein, who has shown the ability to run with running backs and tight ends, and drafted Alex Anzalone, who has shown the range to cover the sidelines, to join the likes of Robertson and Nate Stupar. The team also added Manti Te’o, who has proved to be strong against the run.

Those players, paired with rangy safeties such as Vaccaro, Vonn Bell, Marcus Williams and Rafael Bush, have given New Orleans a defense that has a potential to get around the whole field and get there quickly, a necessity in today’s NFL.

“It’s being played more and more in space because of the passing game,” coach Sean Payton said. “I think a lot of it depends on the scheme you’re looking for, what you’re playing, how much man (defense) you’re playing versus zone. Everyone has a prototype of what they’re wanting from the (middle linebacker), from the weak side; it depends on what you’re doing defensively. But we are seeing a lot more open sets, which require guys to play in space.”

One play in the preseason doesn’t mean much, but it was encouraging to see Anzalone snuff out a pass to the flats during the first half of Saturday’s game against the Houston Texans. It will be even more encouraging when these linebackers show they can make such plays with consistency — and cover shallow zones when New Orleans switches up its coverages.

It’s a must in today’s NFL. It has taken some time to accomplish the task, but the New Orleans defense appears to have a clear plan of action and has spent the past few years checking off the boxes on its list of musts.

It looks like progress is being made. Things appear to be happening faster, but we won’t really know until the real games start.

For now, after a few years on an uncertain path, just being able to see a direction is a win.

Follow Nick Underhill on Twitter, @nick_underhill.​