SEATTLE — The Mariners’ season was starting to develop a feel-good vibe. The team was winning with an appealing blend of personalities. Even a hand injury to Robinson Cano on Sunday didn’t completely change the sense that they might have something special going on.

And then, in one shocking turn of events Tuesday, it all blew up. Not only did Cano obliterate his legacy and probably torpedo his Hall of Fame chances with an 80-game suspension for violating MLB’s drug policy, he hung a dark cloud of gloom — and a gaping hole in the lineup — on a team that needed exactly the opposite.

This was a misstep of massive proportions by Cano, one not explained away by his boilerplate excuse that the substance — a diuretic called Furosemide — had been issued by a licensed doctor in the Dominican Republic.

Sorry, but I’m having trouble buying his claims that it was all an honest mistake. I’ve heard too many athletes over the years staunchly proclaim their innocence, only to have it revealed later that it was all a facade. Who can forget Rafael Palmeiro pounding his fist at the Congressional hearing on steroids and saying, “Let me start by telling you this: I have never used steroids, period. I don’t know how to say it any more clearly than that. Never.”

Five months later, Palmeiro tested positive for PEDs. I sat on a folding chair in Maryvale, Ariz., in February 2012 and listened to Ryan Braun passionately dispute his 50-game PED suspension that had been overturned by MLB arbitrator Shyam Das because the urine sample was mishandled.

“I truly believe in my heart, and I would bet my life, that this substance never entered my body at any point,” he said. “Today is about everybody who’s ever been wrongly accused, and everybody who’s ever had to stand up for what was actually right.”

Eventually, though, Braun was nailed dead to rights through the Biogenesis investigation, accepted his 65-game suspension and finally admitted that he had taken PEDs during his National League MVP season of 2011.

“It was a huge mistake for which I am deeply ashamed, and I compounded the situation by not admitting my mistakes immediately,” Braun said in a statement released by the Brewers.

It’s hard not to be skeptical when every suspended player uses some version of the same explanation: They didn’t know what they were ingesting was banned. Cano insists he did not, and has not, used PEDs. A diuretic can have legitimate medical uses, and Cano claimed he was being treated for a “medical ailment,” which MLB.com’s Mark Feinsand reported was high blood pressure.

But MLB isn’t going to automatically suspend someone just for using a diuretic. One common use of this diuretic, according to ESPN investigative reporter T.J. Quinn, is to mask PED use.

Once the positive test came back before the season, the Independent Program Administrator — a mutual appointment by both MLB and the MLB Players Association to oversee the Joint Drug Prevention and Treatment Program — would have done an investigation to determine if the diuretic was used to avoid detection of a drug. And the fact that the suspension was leveled — with Cano eventually dropping his appeal last weekend, before the hand injury, according to a source — is a strong indication that the finding was of an intent to mask a drug.

The Mariners on Tuesday backed Cano, which is to be expected, particularly in light of the $24 million per year still owed him from 2019 to 2023. Beyond that, Cano has been a great player for them and an asset in the community. Manager Scott Servais said, “We love Robinson Cano. We really do, and what he means to our ballclub and the organization, but just like a family member makes a bad decision or a bad choice, you still love them.”

But the damage done to this once-promising season could be massive. General manager Jerry Dipoto said the Mariners had been looking at Cano’s injury as a two- to four-week absence, even with the likelihood of surgery. That would have been a blow, but something they could work through with a little jerry-rigging of the lineup.

Now they are bracing for three months without the spiritual leader of their clubhouse and the rock in the middle of the order. The ripple effect will be significant as they rob Peter to pay Paul, perhaps moving Dee Gordon to second base but then leaving issues in the outfield.

Perhaps it’s true, as Servais and Dipoto both expressed, that the team will rally around this development.

“I’m sure it will be a psychological blow to this team initially,” Dipoto said. “But this team has a nice, resilient quality to it. So it can be a nice, galvanizing moment where they continue to pull together.”

But Dipoto also admitted he’s optimistic by nature. It’s far easier to envision this suspension casting a pall over what had been an upbeat start to the season. And beyond that, the Mariners, by any measure, simply are not going to be as strong of a ballclub without Cano for roughly half the season. That could easily be the difference in what already was going to be an uphill battle for the team’s long-elusive playoff spot.

For Cano, the damage to his reputation will be in many ways irreparable. One has to look no farther than Seattle teammates Dee Gordon and Nelson Cruz — both of whom were suspended in the past for violations of the drug policy — to see that one’s image can indeed be salvaged. Both are popular and productive players. But it is also a stigma that won’t go away, particularly for a player of Cano’s stature.

Cano was on what seemed to be a certain Hall of Fame path. That is now severely compromised. Palmeiro is the example that should frighten Cano. He exceeded 3,000 hits and 500 homers, each accomplishment enough to punch a ticket to Cooperstown but when combined in one player should make him a first-ballot no-brainer. Yet because of his 10-game suspension for testing positive in 2005, Palmeiro never received more than 12.6 percent of the vote, and he dropped off the ballot after four years when he fell below the requisite 5 percent.

Yes, Palmeiro had the Congressional debacle I mentioned earlier. But many voters — myself included — have grappled with the difficult question of PEDs by drawing a moral line between those who were alleged to have used before the institution of drug testing, and those who tested positive after a policy was instituted. Thus, I have always voted for Barry Bonds and Roger Clemens and have never voted for Palmeiro.

It’s not a perfect solution, but I know I’m far from alone in that distinction even among fellow soft-liners on PED use. Sure, it’s impossible to know how the voters will regard drug violations in 10 years (or longer), when Cano is likely to go on the ballot. But this will haunt him.

It will haunt the Mariners, too. Suddenly, this feel-good season feels pretty lousy.