Rams vice president Kevin Demoff (right) learned the hard way about the pitfalls of the modern draft, and the team’s dry spell cost coach Jeff Fisher (left) his job in 2016 AP

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With most teams busy trying to accumulate draft picks, the Patriots instead took a hard pass on the 2017 NFL Draft.

They traded away their first-, second-, and fifth-round picks for young players with NFL experience: Brandin Cooks, Kony Ealy, and James O’Shaughnessy. Their entire draft haul consisted of a pair of third-round picks, a fourth-rounder, and a sixth-rounder.

This year, the Rams have decided that the draft isn’t what it’s cracked up to be, either. They traded their first-round pick for Cooks, and last year they traded their 2018 second-round pick for Sammy Watkins.

The Rams built their team the expensive way, adding several big veterans through trades and free agency: Ndamukong Suh, Aqib Talib, Marcus Peters, and more. And when the draft is held next weekend, the Rams won’t be on the board until the third round, pick No. 87.

It’s a strategy that the Rams developed through experience — the hard way.

“We learned this through the RG3 trade,” vice president of football operations Kevin Demoff said in February at the MIT Sloan Sports Analytics Conference, referring to the big 2012 trade that sent the No. 2 pick, which would become Robert Griffin III, to Washington.

The Rams emerged from that deal with eight draft picks over three years, including five in the top two rounds. They were supposed to be locked and loaded with young talent, ready to take on the NFC for years to come.

Six years later, only one player is left: defensive tackle Michael Brockers, he of 19 sacks in six seasons. Left tackle Greg Robinson, a No. 2 overall pick, was a huge bust and lasted just three years. Cornerback Janoris Jenkins was allowed to walk in free agency after four years. Linebacker Alec Ogletree provided five serviceable seasons, and was just traded away to the Giants. Running back Isaiah Pead and wide receiver Stedman Bailey had their careers cut short by freak accidents. Zac Stacy and Rokevious Watkins flamed out quickly. And coach Jeff Fisher was fired after five playoff-less seasons.

The problem, the Rams found out, was that they didn’t have enough time to develop their young players, thanks to the new practice rules established by the 2011 collective bargaining agreement.

“In the new CBA, you get such limited time with players,” Demoff said. “Going really young, I think, was easier when you had more time in the offseason, more time in training camp. We had a player last year who missed all of the offseason because he didn’t graduate until late, and he had 10 practices until the preseason opener.

“It’s great to have picks, but even if you hit on them, how they develop is so much harder now. You don’t necessarily have three years to develop these guys.”

Greg Robinson, the second overall pick in 2014, lasted three years with the Rams. rick scuteri/AP

The NFL Draft is still important, of course. But the reasons have changed under the new CBA. And a good case can be made that the draft just isn’t as important as it used to be.

“I still think [building through the draft] is the best way to go, but you’ve got a lot more options now, and it’s not the only way to go and the only way to win,” former Eagles president Joe Banner said.

The biggest change in today’s NFL: Time, not money, is the scarce resource.

In the pre-2011 NFL, when teams held 50-odd full-contact practices before the start of the season and salary-cap space was tight, signing expensive free agents and eschewing the draft was the quickest way to miss the playoffs (just ask the early 2000s Redskins). There was almost no debate across the league that the best method for building a roster was to draft and develop.

“There was a correlation for many years between the teams that had the most draft picks and the teams that were the most successful — Pittsburgh, the Patriots, Eagles, Ravens,” said Banner, whose team reached the playoffs 11 times between 1995-2012. “Those were the teams that were leading the draft every year.”

But the new CBA has shifted the dynamic, making veterans more valuable and rookies less so.

The biggest reason has been the reduction in practice time. Teams used to hold full-contact practices in the offseason, two-a-days during training camp, and had no limitations on full-contact practices during the regular season.

But under the new CBA, spring practices are strictly regulated with no contact, no pads, and only four hours per day at the facility. Two-a-days in training camp have been eliminated, and teams can hold only 14 padded practices throughout the entire regular season.

These restrictions are great for the players’ health and safety, but terrible for developing young players — especially those that play in college offenses that don’t translate to the NFL.

“It’s definitely a big problem,” an NFC general manager said. “It’s just a lot harder to develop players, especially if you’re starting over with a new coaching staff and trying to implement a new system.”

Teams are limited in the amount of full-contact practices they can have. barry chin/globe staff file

Demoff said that the Rams ran a study, and concluded that it now takes players about three years to have the same amount of practice time they would have gotten in one year under the old CBA.

Young players usually get a couple of years to prove themselves, but if they don’t make immediate contributions, teams move on quickly.

“It’s not baseball, where you have the minor leagues and then six years of service,” Demoff said. “So if you go really young, you’re not finding out until Year 3 or 4 if they’re any good, and then you’re paying market rate for them.”

The RG3 trade loaded up the Rams with young talent, but, said Demoff, “We looked at it as [we needed] a better balance. We were the youngest team in the league for four years, five years, but you have to find those veterans to plug in.”

Offensive linemen used to be the easiest and safest players to project to the NFL, but in the last five years, top-10 picks Luke Joeckel, Jonathan Cooper, Chance Warmack, Ereck Flowers, and Robinson have all been busts.

“It went from the easiest and safest pick to one where we’ve seen a lot of misses,” Banner said. “Now, does that mean things have really changed, or it’s just we’re in a down cycle at the moment? I don’t know, but there is no doubt that there are some positions in the league that had a higher batting average, and that doesn’t seem to be as true anymore.”

And the Patriots also love to flip their mid- and late-round picks — which have a lower chance of becoming NFL players — for established players. This year they got Danny Shelton, Cordarrelle Patterson, and a sixth-round pick all for a 2019 third-rounder. They traded a sixth for cornerback Jason McCourty and a seventh. They traded a seventh for linebacker Marquis Flowers.

The Patriots enter next week’s draft with five picks in the top 95, but they traded away all four of their picks in the fourth and fifth rounds.

“They’re trading a fourth-round draft pick, where you have a 15 percent chance of having a good starter coming out of the fourth round, for guys that are already established as good players,” Banner said. “How can that not be smart?”

The other big change in today’s NFL is that the league is awash in salary-cap space. The cap has consistently risen by $10 million-$12 million each year, from $123 million in 2013 to $177.2 million in 2018, thanks to an influx of TV money. And the new CBA allows teams to roll over any unused cap space to the next year (the Browns rolled over $58.9 million this year). The 49ers entered the offseason with more than $100 million in cap space, while 20 teams had $20 million in space, and 12 teams had $40 million.

So adding a veteran — or two, or five — isn’t as cost-prohibitive as it used to be. The Eagles just won the Super Bowl with free agents Alshon Jeffery, LeGarrette Blount, Chris Long, Timmy Jernigan, and Torrey Smith all playing crucial roles. Their opponents, the Patriots, also went with the veteran approach, and haven’t used a first-round pick since 2015.

And the trade market has exploded, as teams are getting wise to the Patriots’ young-veteran philosophy, and because of all the salary-cap space. There have been 21 trades this calendar year, compared with 10 through this time last year, and four in 2016. Taking on veteran contracts, or dead money to get rid of a veteran contract, isn’t a big deal anymore.

“The cap used to be so tight that teams couldn’t even contemplate taking a veteran on that was making any real money,” Banner said. “Now the huge amounts of cap room that most teams have changes both the value of veterans players making a lot of money, and draft picks.”

The draft may not be as important as it used to be, but it still carries plenty of weight. Teams can punt on the draft once or twice, but they can’t continually ignore it. The Patriots are reversing course this year and loading up with multiple picks in each of the first two rounds.

But whereas draft picks used to be counted on to be the cornerstone of a team, now they are viewed more as low-cost and fill-in-the-gap type players. The new CBA instituted a new rookie wage scale that has made most rookies tremendous values — locked in at below-market rates for four seasons.

With most starting quarterbacks now making $20-plus million, Jameis Winston has a cap number of $8.06 million this year. Trey Flowers, the Patriots’ terrific young defensive end, made about $2.1 million in his first three seasons combined, and will make $1.9 million this year.

“Long-term, you can’t balance the economics without a fair number of these younger players coming in and making a difference and playing and being less expensive,” Banner said.

But with teams awash in cap space, and young players not getting the coaching and development that they need, the importance of the draft just isn’t what it used to be.

“I’m never going to join the school that thinks trading away all your draft picks is a smart thing to do,” Banner said. “But I’m saying relative to where it was six, seven years ago, when teams desperately needed those picks to just manage their cap, those picks have lost a bit of their value. That’s the underlying change in how some teams are building their rosters.”