John Schneider and Pete Carroll know they have wasted two years of their great defense because of a poor offensive line — one that is even worse than the middling units they had as they reached the Super Bowl in 2013 and 2014 — and the team’s chiefs apparently have had enough.

Fans have been calling for them to add a good left tackle since Russell Okung left after the 2015 season. After using Bradley Sowell, George Fant and Rees Odhiambo over the past two seasons, they finally did it — Schneider pulling off his second blockbuster deal in two months to add another Pro Bowl player.

Some think Schneider is selling the future for one last hurrah, but he’s really just making sure the Hawks don’t waste this window any more than they already have. And he’s doing it at little cost to the future.

Duane Brown should immediately improve, upgrade and settle the left tackle spot — enabling the Seahawks to free up tight ends to help inconsistent right tackle Germain Ifedi. With Brown on his left and Justin Britt on his right, rookie Ethan Pocic should develop quickly as he starts at left guard for the injured Luke Joeckel. And when Joeckel returns, the Hawks should be able to pick the best of two decent options. It doesn’t hurt either that Brown is reunited with former Houston teammate Oday Aboushi, now Seattle’s right guard.

The Seahawks can’t run the ball (just 97.6 yards per game), and Brown alone is not going to fix that problem. But, if he and Pocic can develop a rapport over the next few games and create a push on the left side, the Hawks could start to gain ground.

In the meantime, Russell Wilson shouldn’t have to run from left-side pressure as much as he has with Odhiambo at left tackle.

Brown cost the Seahawks a fair penny, but the three-time Pro Bowl tackle should be worth it — even at age 32.

Schneider had been trying to move Jeremy Lane and his $4 million salary for weeks, so he was lucky Houston bit.

Schneider told reporters that Seattle is taking on Brown’s contract at face value, but “we want him to finish his career here and have him be here for several more years.” That sounds like Schneider will try to work out an extension for Brown, who is signed only through 2018 right now.

An immediate extension might not be in the cards due to lack of cap space, but the Hawks have to make room for the remaining $5 million on Brown’s 2017 salary. Removing Lane freed up $2.1 million, leaving $2.9 million. The Seahawks have only about $1.4 million though, so they might pay Brown’s $5 million salary in advance, making it a prorated bonus that would require just $2.5 million for this year’s cap (and pushing $2.5 million to 2018). The Hawks could cover that and still have about $1 million left for the rest of the season (with more available via simple restructure of another contract).

The Hawks also could get Brown to take a temporary pay cut in a new deal that defers the signing bonus to next offseason. If they pay him $2 million the rest of this season, they could then pay him what amounts to an option bonus in March, on a new deal for maybe three more years and $11 million a year. They also could just get Wilson to convert some salary to bonus (UPDATE: This is what they did).

As for the draft, the Hawks are now without their second-rounders in the next two years — given up for Richardson and Brown — but Schneider has two aces in the hole: (1) He always trades out of the first round and adds more picks anyway and (2) he knows he is going to get some good comp picks in 2019.

Schneider has made 12 trades this year, the most since his first year as Seattle’s general manager in 2010. Eight of his deals have come since late July — that’s the most veteran deals he has ever made. He has acquired Matt Tobin, Justin Coleman, Isaiah Battle, Richardson and Brown and traded Jermaine Kearse, Tramaine Brock, Cassius Marsh and Lane.

Seattle’s 2018 draft now includes these picks by round: 1, 3, 4, 5, 7, 7. Figure Schneider will flip the 1 for at least a 2 and 4, and he might also trade Richard Sherman.

The 2019 draft is short only the 2, and the Hawks could end up with a 3 for Richardson, plus two or three other picks for guys such as Joeckel, Jimmy Graham, Paul Richardson, Eddie Lacy and Luke Willson.

So, no, Schneider has not mortgaged the future to improve the present. He knows exactly what the Hawks can afford to pay to become more competitive than they have been the past two years.