Justin Coleman is the lone Seahawks CB with serious NFL experience. / Drew McKenzie, Sportspress Northwest

Leading off, Philip Rivers. Batting second, Jared Goff. Hitting third, Aaron Rodgers. And at the cleanup spot, Cam Newton.

If you’ve been following this ruthless little four-week run of of top-shelf NFL quarterbacks, you know that the Seahawks are 0-2 against the Chargers’ Rivers and the Rams’ Goff, and face No. 3 Rodgers Thursday (5:20 p.m., FOX) at the Clink. Worthy of note is that the Green Bay Packers have won the past three games between the teams by a combined score of 82-36.

And those three outcomes were before the Seahawks decided to start a rookie and two second-year players in the secondary to replace the Legion of Boom.  To say Rodgers is savoring the Seahawks matchup is to say Willy Wonka knows how to find chocolate.

For as much kvetching as there has been over Russell Wilson’s mistakes, the Seahawks offense has put up 31 points in each of the losses to the Rams and are now the top rushing team in the NFL at 152.2 yards per game.

But they are 4-5 and hanging onto the cliff’s edge regarding playoffs because they have fallen to 12th in team defense (346.9 ypg), thanks largely to an inability to keep offenses  from igniting multiple explosive plays every game.

Two episodes were particularly egregious.

In each of the past two games, the Seahawks have allowed the longest gains of the game on third-and-15. Against the Chargers, Rivers hit WR Keenan Allen for 54 yards, and against the Rams, Goff hooked up with WR Robert Woods for 34 yards.

Both were uppercuts that stunned the Seahawks and altered outcomes by sustaining long TD drives when punts were imminent.

The gunslingers were good. Goff was 28 of 39 passing for 318 yards, two TDs and no picks (113.0 passer rating). He was sacked twice for 11 yards in losses. Rivers was 13 of 26 for 235 yards with two TDs and one pick (105.9 passer rating). He was sacked twice for 13 yards.

Obviously, many things beyond bad coverage on single plays contribute to a defeat. But the continuing vulnerability of the defense to crossing routes at medium depth likely has been an object of furious note-taking by opposing offensive coordinators.

All of the OCs rejoice in the same discovery: They are not making notes that require exclamation points around No. 29, Earl Thomas.

The injury loss of the All-Pro free safety is no longer publicly discussed among the Seahawks. But it is an object of relief for each opposing veteran QB who had had to account, coming into a Seattle game, for Thomas, CB Richard Sherman and SS Kam Chancellor on every play.

Three replacements, CBs Tre Flowers and Shaquill Griffin and FS Tedric Thompson, may someday excel. But for now, they’re just guys aspiring to be NFL average. That’s what happens with the installation of youth — they first must learn to be assignment-correct before venturing into the risk-taking that was a hallmark of the Legionnaires.

SS Bradley McDougald (sixth season) and nickel back Justin Coleman (fourth season) are the two guys in the secondary with some seasoning. McDougald, who has played with and without Thomas this season, described the difference.

“Earl has a presence,” he said Tuesday. “You feel him. You kinda know where he’s going to be, what to expect. It’s not any knock on Tedric — I feel like he’s doing a great job. But Earl sees things faster, he might read things faster. A lot is just experience.

“When you get groomed from a young age, you start to see things. You read the routes, the patterns, the game slows down, and you’re moving faster, and it shows on tape.”

The young guys simply don’t know what they don’t know.

Responsibility for the passing yards are not all on them — the Seahawks pass rush has yet to be steadily disruptive — and coach Pete Carroll is reluctant to fault the kids.

“It’s not that easy, just (blaming) experience,” he said. “(The Rams) run a lot of crossing routes. We were playing man-to-man and we mixed some zones and they got a couple  in each. They hit us in both ends of our coverage stuff. There were a couple big, significant plays.”

He said the linebackers were responsible for Woods’ big gain.

“That was a really poorly-played play,” he said. “We got caught up cheating on the coverage (with) guys looking at the wrong stuff.

“The linebackers and underneath coverage should be deep enough to discourage that throw, so (Goff) should dump the ball under them, not underneath the DBs and the safeties on the deep end. There’s another whole level we should’ve been protecting to make them force the ball way underneath.”

Carroll knows there’s no way around trials by fire.

“Inexperience sometimes does play into it,” he said, then switched into first-person to describe the player’s dilemma: ^“‘I don’t want to bite on the route underneath me. I’ve got to stay deep and be a little more poised about it.’

“(Inexperience) certainly showed up. That’s always a problem. But I don’t think it’s the only problem.”

Then comes Thursday’s wrinkle: Since the non-Rodgers portion of Packers’ passing game has had problems this season, they’ve become ground-pounders like the Seahawks. Behind leading rusher RB Aaron Jones, a fifth-round pick a year ago from Texas-El Paso, the Packers average more yards per run (7.8) than per passing attempt (6.1). Jones leads the NFL in yards per carry (6.77).

Additionally, LB K.J. Wright (knee), who couldn’t finish the Rams game, has not practiced in this short week. His likely absence Thursday will extend the grin on Rodgers’ mug.

The 4-4-1 Packers aren’t without their flaws, but they do have a nearly identical urgency to win to stay relevant, and they have Rodgers.

Said Wilson Tuesday: “There’s only a few guys in the world, at every position, when you think about guys making plays in tough moments — like, how did he do that? – he’s one of those guys.”

He’s the toughest out in the lineup facing the Seahawks.