With a defense in training, the Seahawks absolutely need Russell Wilson to play his best this season. And it starts on first downs.

That’s what made it so disappointing when Seattle came up short in the opener in Denver — Wilson holding the ball too long and taking unnecessary sacks and Brian Schottenheimer doing very little to help him as the Hawks basically ran their old playbook.

Pete Carroll seemed to put most of the blame for Seattle’s offensive problems on the offensive line — “he got hammered” — but he admitted Wilson “can play way better than that.”

As usual in Seattle’s losses, Carroll pointed to third downs (2 of 12) as a big culprit: “There were too many third-and-longs. From third-and-9 up, there were six or seven of them — and that’s enough to wreck your day.”

But how do you get to third-and-long? By screwing up on first down. In Denver, the Hawks had the same problems on first downs they always have in season openers.

Since Wilson became QB in 2012, the Seahawks rank 23rd in the NFL on first downs in openers — 4.74 yards per play. In Denver, outside the 66-yard play by Will Dissly, they averaged just 2.56 yards on first downs.

That is not an offensive line problem; it’s a quarterback and scheme failure.

On the first play, Wilson had plenty of time and had a receiver wide open, yet he hesitated — and lost. The QB should never be sacked on first down — yet Wilson ran himself into sacks twice on that down, and he also fumbled on first down on the final desperation drive.

The Seahawks succeeded (i.e., gained at least four yards) on just 8 of 25 first downs. Rashaad Penny got the ball on first down six times and failed five times, losing yards three times. Chris Carson was 3 of 7 on first downs; he would have been 4 of 8, but J.R. Sweezy’s bad hold negated a 44-yard gain on a pass.

“We didn’t run the ball well enough to offset their rush,” Carroll said, adding that Von Miller (three sacks) and Denver’s athletic front contained Wilson all game.

“Sometimes, when he takes off, great stuff happens, and sometimes you run into trouble,” Carroll said. “And it happened a couple times (in Denver). They were a very athletic rush and they did a really nice job and they were able to get him down. A couple times, he almost got away when he’s rolling out and a (defender) trips him — that’s the difference between a big play or not, possibly.”

When facing a great pass rusher, the way to attack is to (1) throw quick passes and (2) run the ball right at him to wear him down. The Hawks didn’t do either against Miller, but they need to adjust for the next game-wrecking pass rusher, Khalil Mack, in Chicago on Monday.

Schottenheimer needs to do better than recycling Darrell Bevell’s play script. We thought he was going to bring some creativity, but the Hawks ran more of Bevell’s 70 percent than Schottenheimer’s new 30 percent. So we saw the same horrible screen game (both running backs and receivers) and very little misdirection or bootleg action. About the only new stuff we saw were slants by the tight end — Will Dissly had a big day because of it.

We have argued for years that the 5-foot-11 Wilson should often roll out so he can scan the entire field and have a run/pass option, but the Hawks refuse to do it very much. He has done well from the pocket when not pressured; but, facing tough pass rushers, he needs to proactively move so guys like Miller and Mack cannot locate him so easily.

The good thing is the Hawks are past the opener, so they should start to improve a bit. Since 2012, the Hawks have averaged 4.74 yards on first down in openers and bumped up to 5.48 (seventh in the NFL) over the next 15 games.

Their third downs have correspondingly been better. In openers with Wilson, they have averaged a league-low 3.31 yards on third downs and converted just 31.7 percent (29th in the NFL). But, in the ensuing 15 games, they have upped their gains to 5.64 yards (10th) and the conversion rate to 39.3 percent (tied for eighth).

Let’s hope the first-game jitters are out of the way and Wilson and Schottenheimer start doing their part to help a youthful defense that needs time to develop.