The Dodgers melted down spectacularly in Pittsburgh tonight, blowing a 5-4 lead in a nine-run Pirates seventh inning. It ended 13-6, with the Pirates completing a sweep of the most expensive team in baseball.

This game had the feel of a milestone, a turning point, even from the other side of the Atlantic.

Consider:

–Another rocky start from Alex Wood, one of the two starting pitchers the Dodgers picked up at the trade deadline but who have struggled. Mat Latos, the other guy, has one strikeout in 10 innings as a Dodger, against 11 hits, two walks, two homers and seven runs.

—Yasiel Puig continues to demonstrate he is the biggest knucklehead in ball. Reduced a couple times per week to duty as pinch-hitter/defensive replacement by the return of the ghost of Carl Crawford … he contrived to make a throwing error in his two innings in the field. Earlier in the series, he made a poor decision in making a throw, which set up a Dodgers loss in extra innings. (He makes lots of bad decisions.)

—Jim Johnson. This is the real fault line here. The Dodgers have struggled to bridge the gap between starting pitcher and Kenley Jansen this season, and Johnson, the Atlanta Braves closer before the Dodgers traded for him, week before last, has been awful. He has made four appearances with the club and blown two saves and taken two losses. He has allowed 12 runs in 3.2 innings, with 11 hits, three walks and two home runs.

Tonight, Dodgers manager Don Mattingly left Johnson in the game for most of the Pirates’ nine-run seventh inning, which struck me as a punitive sort of thing. “You’ve been a disaster; you’re on your own.” He could also argue, later, that his bullpen was depleted.

However, a Dodgers fan who watched the game on national television, a friend of mine, saw a bigger picture on display in Pittsburgh. A more informed analysis. And a very insightful and fascinating one, in which he suggests the final game of the Pirates’ sweep may have been a turning point for Mattingly and the Dodgers, and between the manager and his bosses, Andrew Friedman, president of baseball operations, and Farhan Zaidi, general manager — focusing on Mattingly’s decision to leave Johnson in there for that spectacular meltdown on the Fox Sunday night game.

Here is that analysis:

“That’s the real story, yeah, Mattingly leaving Johnson out there. He struck out the first guy, hit the second guy, and then it was batting practice, everybody hitting rockets, one after another.

“Mattingly had Howell warming up behind him, but once the Pirates took the lead, he sat Howell down and just left Johnson dangling.

“I don’t know that Mattingly was deliberately punishing Johnson per se, although that was certainly the effect of his inaction, and it seems certain to erode whatever support Mattingly might still have in the clubhouse. I think this was Mattingly, knowing he’s probably gone after the season anyway, flipping a big, nationally televised eff-you to Friedman and Co., saying to management, OK, this is the dreck you’ve given me to work with? Fine, this is what you get.

“I’m sure he’s [ticked] that the SPs they got at the trade deadline, Latos and Wood, have been no better than the crap retreads they’d been running out there in the 4-5 rotation spots all year (Wood lasting only five innings laid the groundwork for tonight’s disaster), and that Johnson, the other big deadline acquisition, has been drilled every time Mattingly has used him.

“And, I don’t think it was a coincidence that when he finally did lift Johnson, the guy he brought in wasn’t Howell, but Peralta, management’s big bullpen “get” last winter, who’s also been consistently awful. Another little eff-you to Friedman, that move.

“This might be a pivotal moment in the Dodgers season, an embarrassment in the featured Sunday night national-TV game in which the Dodgers manager brazenly thumbed his nose at Dodgers brass. Now we’ll see how management responds.

“Mattingly could be gone by the end of the week, if not sooner. Or they could let him finish out the string and make a change in the offseason.

“This was as ugly an episode as they’ve had in a while … as ugly as Jim Johnson’s pitching line, maybe the worst I’ve ever seen for a reliever.

“They hardly even look like a team right now; more like a rudderless, leaderless, character-less collection of mercenaries. They can’t beat anyone who’s any good; they’re now 11 games under .500 against winning teams. And now the manager is in open warfare with his bosses.

“And they’re in first place. What the hell?”

A more dispassionate view of what went on, pegged to the failures of the Dodgers’ trade-deadline acquisitions, can be seen on ESPN.com, by Mark Saxon.

Anyway, the Dodgers are the worst good team I can remember, and it was on display this weekend in Pittsburgh.

They have the highest payroll in baseball, but they still haven’t played in a World Series since 1988.

The fans are getting restless.