When the Seahawks drafted four defensive backs in April, Pete Carroll said the new crew might end up being the best bunch of backups in the NFL over the next couple of years.

That’s because Carroll knew he wasn’t ready to blow up the Legion of Boom quite yet. The new deal given to Kam Chancellor this week proves that.

With Chancellor signed (through 2020), Seattle’s elite starting defense is set to remain intact for the next two seasons (unless Richard Sherman gets traded).

The Seahawks are quickly approaching a crossroads, though — the point where they will have to start moving on from some of their longtime core players if they are going to remain competitive.

Earl Thomas said he was watching Chancellor’s contract situation “very closely. You want to see, because I feel like we’re all right around the same age. They’re bringing a lot of new guys in. If the writing is on the wall, I want to be able to see it, because I could be next.”

Odds are Thomas will see a third contract in Seattle, too. But others might not.

In the past two drafts, the Seahawks have picked 11 players in the first three rounds who should end up comprising much of the team’s core in 2019 and beyond.

That group includes offensive linemen Germain Ifedi, Rees Odhiambo and Ethan Pocic; defensive linemen Jarran Reed, Malik McDowell and Nazair Jones; defensive backs Shaq Griffin and Delano Hill; running back C.J. Prosise; wide receiver Amara Darboh and tight end Nick Vannett.

The offensive linemen are belated replacements for players already gone — and a hedge for one who might leave. The D-linemen are moves the team hopes will create an elite front in the short term (assuming McDowell can play) and keep the interior strong for the next three or four years. The rest are potential long-term replacements for guys such as Sherman, Chancellor, Jermaine Kearse and Jimmy Graham.

As Carroll and his staff try to pull the squad together on the field, John Schneider and salary cap specialist Matt Thomas are determining how they want to reconfigure their spending in the next two years, when about a dozen core players are due for new deals.

It started with extending Chancellor, and decisions on Graham and Justin Britt are next.

Graham is already the highest-paid tight end in the league, at $10 million a year. Travis Kelce, Rob Gronkowski and Jordan Reed are all over $9 million. That means the Hawks won’t have to give Graham a pay hike if they decide to extend him. He will be 30 in November, though, and the Hawks might not want to keep paying him — especially if they finally realize they really haven’t used him to best effect.

The Seahawks drafted Vannett last year and apparently almost traded up for a tight end in April’s draft. Luke Willson, surprisingly re-signed to a one-year deal this offseason, would be a cheaper keeper. And the Hawks could end up netting a decent comp pick for Graham in 2019.

Britt has just one good year under his belt at center, so the Hawks might want to see him play well for most of 2017 before trying to extend him late in the year. They also have Pocic as a possible backstop for losing Britt in free agency next year.

But it sounds like Carroll wants to create continuity on the line.

“We would like to keep these guys together and really build with them, see if we are able to do that,” Carroll said earlier this offseason, “because we think we really have a nice nucleus right now.”

The Seahawks have flipped the ledger with their line the last few years. Since fielding the top-paid unit in the NFL ($28 million, 21 percent of Seattle’s salary cap) in their 2013 Super Bowl year, they have dropped to the lowest-paid. This will be the second straight year they will spend the least on their O-line, with $16.3 million counting for 10 percent of the team cap.

“If you noticed, when guys came to their next contract, we had to move along,” Carroll said, referring to basically the entire Super Bowl XLVIII unit. “That’s happened a few times to us because of the cap issues. We like the guys we’ve picked over the years, but they’ve had to move on just because of the numbers they were able to generate in the free market. … But that’s because of other decisions we made, and you have to give and take a little bit.”

Now it might be time to give a little bit more to the line.

The going rate for a top-10 center is around $8 million a year, so that looks like Britt’s price, assuming he plays to the same level in 2017. Schneider could pay him before he hits free agency — unless the Hawks prefer to replace him with the cheaper Pocic in 2018.

Luke Joeckel is the highest-paid lineman right now, on an $8 million prove-it deal. He seems likely to start at left guard — unless George Fant fails to improve vastly at left tackle. If Joeckel plays well enough to merit a new deal in 2018, the price will vary depending on where he plays. If it’s tackle, he could follow the path of Russell Okung, who parlayed a 2016 prove-it deal with Denver into $13.25 million a year with San Diego. If Joeckel plays at left guard, the free-agent price might be more like $9 million (six guards signed deals averaging $9.3 million this offseason).

That difference in price might explain why the Hawks are hoping the ultra-cheap Fant can hold down left tackle.

However it works out, Schneider has to decide whether he is prepared to pay two offensive linemen next year — or stay cheap with a unit like Fant, Odhiambo, Pocic, Mark Glowinski and Ifedi.

Also next offseason, Schneider and Carroll will need to make decisions on several other key players who are set to be free agents in 2019 — Sherman, Thomas, Cliff Avril, K.J. Wright, Frank Clark, Tyler Lockett.

Sherman seems more likely to be traded than extended — Schneider has referenced saving money and getting younger as reasons the team is open to trading him.

Thomas and Wright, who both will be 30 in 2019, seem like good candidates for extensions next year — assuming they continue their stellar play in 2017.

Avril will be 33 for the 2019 season, and the team probably won’t extend him before his deal expires because they will want to see how he plays in 2018. They might not extend Clark either. Rubin will be 33 for 2019, too, and could be let go after this season, if Reed and Jones prove capable of shutting down the run.

Lockett could be a costly re-up — along the lines of Baldwin’s $11 million — but the multiple threat is worth it.

The Seahawks are projected to have $21 million in space on an assumed $178 million salary cap in 2018. If they were to trade Sherman and release Jeremy Lane and Kearse, they could add another $20.75 million.

That could allow them to extend Britt and/or Graham on market deals and still have at least $27 million. If they kept Sherman, it would be more like $16 million — basically $11 million available for free agents and extensions.

Now you can see why they are willing to trade Sherman. If they don’t deal him, they will have to forgo some other extensions and/or let a few other guys go in free agency next offseason.

Among the notable free agents in 2018: prove-it-deal signings Eddie Lacy and Bradley McDougald, plus one-year returnees DeShawn Shead and Willson, 2014 draft picks Paul Richardson and Cassius Marsh and restricted free agent Thomas Rawls.

Schneider and Thomas will weigh what they can afford for each and — as always — stick to their price. If they can’t make deals, they will let them go — and take the 2019 comp picks that come their way. (This was definitely part of Seattle’s free-agency strategy this year, with eight one-year UFA deals.)

Projected price points if they perform well:

Eddie Lacy: $6 million. Running backs are devalued in today’s game, so Lacy is unlikely to surpass this figure. He and Rawls are probably running against each other for a Seattle payday — Rawls will be an RFA in 2018 and surely would love to merit the high tender (about $4 million).

Bradley McDougald: $2 million to $4 million. If he plays enough to show his wares, he could parlay it into a medium-sized deal from some team. Now that the Hawks have extended Chancellor, it is hard to see them re-signing McDougald in 2018 — unless Hill is a total bust or McDougald will return for the same salary he took this year.

DeShawn Shead: $2 million to $6 million. He might not get enough playing time to chalk up a good payday. If Griffin or Neiko Thorpe steps up, Shead will be at the mercy of a market that was just watered down by the great corner class in this year’s draft. If the Hawks trade Sherman and/or cut Lane, though, the Hawks probably will pay him what they paid Lane ($6 million) and go with Shead, Griffin and Thorpe as their 2018 corners.

Luke Willson: $2 million. The backup tight end surprisingly returned to Seattle on a one-year deal worth $1.8 million. He obviously didn’t have much of a market. With a bunch of good tight ends entering the league this year, it’s possible Willson won’t get an offer that’s any better next year. If the Hawks keep Graham, they won’t offer Willson much.

Paul Richardson: $2 million. P-Rich has not lived up to his second-round status, and the Hawks won’t pay much to keep him, no matter what he does in 2017. They have Doug Baldwin and Tyler Lockett and just invested another third-round pick in receiver Amara Darboh.

Cassius Marsh: $1 million. Marsh has turned into an excellent special-teamer and good rotational pass rusher, but the Hawks are not going to pay much to keep him.