Kevin Long is in his 10th season as a big-league hitting coach. In that decade, he has witnessed just how quickly fortunes can turn.

“I’ve seen all sorts of stuff happen,” said Long, who is entering his second season with the Mets. “As a matter of fact, we got no-hit twice last year and went to the World Series, so explain that? And the Dodgers got no-hit twice and we were playing them in a playoff series. So, strange things happen in baseball.”

That strangeness manifested itself once more, this time with a lingering offensive funk that has turned the Mets into unwilling participants of a stress test. And again, they find themselves forced to simply ride it out.

“We have enough veterans on our team that we’ve been through it, especially since we’ve been through much harder times than we’re going through right now,” cleanup-hitting first baseman Lucas Duda said. “I feel like there’s no need to overreact or panic. We’re just seven or eight games deep. You’ve got to sort of bear with it, as do the fans. We’re in a bit of a funk.”

After a winter spent retrofitting the lineup — highlighted by the re-signing of Yoenis Cespedes — the Mets’ bats have yet to emerge from hibernation. They rank at or near the bottom of several major categories.

Entering Thursday, they were dead last in average (.194), slugging (.250) and OPS (.535). They’re 25th in on-base percentage (.285), despite placing in the upper third of baseball with 30 walks, an indictment of how little they have put the ball in play with success.

Perhaps most striking, the Mets’ 20 runs scored through their first eight games place the Mets ahead of only the 0-9 Twins, who have scored 14.

“There’s been some poor days when we just haven’t swung the bat well and then there’s been some days when we’ve hit some balls hard and for whatever reason they’ve been at people or the wind was blowing in that day,” Long said. “I think the main thing we’re talking about here is that it just hasn’t clicked, and it hasn’t clicked on all cylinders.”

With a lineup stocked with established bats, the defending National League champions have little in common with the dreadful clubs from the franchise’s earliest days. Yet that’s the company they find themselves in when the offensive start is viewed from a historical perspective.

The Mets have slugged only two home runs, better only than the 1970 team, which managed just one round-tripper through the season’s first eight games. Their .194 average is the fifth worst mark in team history.

And the Mets’ .250 slugging percentage to this point is second worst behind only the hapless 1963 Amazins’, who went 0-8 to begin a 111-loss campaign.

But it’s not just a power outage plaguing the Mets. Through eight games, they have yet to plate a run with a sacrifice fly, an indictment on their situational hitting.

That’s happened just once in team history, back in 1964, when they began 1-7 on the way to 109 defeats.

“Right now we’re just not at that point where we’re putting pressure on the opposing team and getting base runners out there,” Mets captain David Wright said. “It’s almost like, again, you get one shot maybe two shots to score runs in the game, and if you don’t do it, it’s not happening.”

The Mets’ 3-5 start has stemmed in large part from an offense that has mustered just 2.5 runs per game — a trend that Long is convinced will not continue.

“I have a lot of faith in these guys and their track records will prove that they’ll hit,” he said. “We’ll trust the process, stay diligent in our work, keep after it, and it will change.”