Problems are never completely solved in baseball.

That’s what makes this game such a challenge. Catcher Travis d’Arnaud knows this better than anyone.

D’Arnaud was off to a terrific start at the plate and behind the plate. Then he was hit on the right hand by the Marlins’ A.J. Ramos in the seventh inning Sunday at Citi Field.

When he got word his hand was fractured, d’Arnaud cursed his luck. Injuries have dogged his career.

“I’m good now, though,’’ he said in the clubhouse after the Mets won their eighth straight and remained undefeated at home, a most costly 7-6 victory over Miami. “That’s life.’’

The baseball gods are always testing.

“I can’t stress enough how invaluable Travis has been over the first two weeks of the season both behind the plate and as a hitter,’’ GM Sandy Alderson said. “Everything has improved defensively and he’s been outstanding offensively as well.’’

A catcher is the heart and soul of a team. When that catcher can hit, he’s even more valuable. D’Arnaud leads the Mets with 10 RBIs. This is about as costly an injury as a team could suffer.

Kevin Plawecki was called up and will start. He is talented. The Mets will learn if he is ready.

Right-hander Hansel Robles will join the bullpen.

Problems are never completely solved.

Alderson knows this better than anyone.

He thought he solved the left-handed reliever issue when he acquired Jerry Blevins and Alex Torres near the end of spring training.

Then came Sunday’s seventh inning.

Blevins was hit in the left arm by a smash off Dee Gordon’s bat, breaking Blevins’ forearm.

One inning, two broken bones. Blevins at the top of the inning, d’Arnaud in the bottom.

“That’s a bad combo in the same day,’’ Alderson said.

The Mets have lost David Wright (hamstring), closer Jenrry Mejia (steroid suspension) and now d’Arnaud and Blevins.

Despite all that, they sit atop the NL East with a 10-3 mark. The 1986 Mets started 10-3. So did the 2006 Mets.

How will these Mets get through this?

With the depth they think they have accumulated, the veteran leadership of Michael Cuddyer, Wright and Curtis Granderson and with that next-man-up attitude.

“[Blevins] was great the first couple weeks of the season, and he’ll be great when he comes back,’’ Alderson said. “In the meantime, somebody is going to have to step up.’’

D’Arnaud praised Plawecki, saying, “This is part of the game, we just have to keep trying to win every single day. That’s what we all want and that’s what we are all striving for, the playoffs, still.’’

Terry Collins knows the reality.

“It’s a tough day for us,’’ the manager said.

What was the mood in the dugout on this broken day?

“Dead silence,’’ Collins said. “They’re big losses. We have to pick up the pieces and move forward.’’

Matt Harvey made it through even though he was so sick, he didn’t think he would be able to pitch as the Mets swept the Marlins in a four-game series for the first time ever.

The Mets trailed early, marking this as their sixth come-from-behind win of the year, the most in the majors.

Now comes a different type of comeback.

The Mets still have their two aces in Jacob deGrom and Harvey.

And guess what? The next time they start will be against the Yankees on Friday and Saturday at Yankee Stadium. As long as they have their aces, these Mets can overcome a lot of misfortune.

Yes, the Mets still have their aces, they still have their most valuable hitter in Lucas Duda, their backbone in Cuddyer and closer Jeurys Familia, who retired Giancarlo Stanton with the potential tying run at second base to end the game.

Problems are never completely solved.

These Mets still have a lot going for them.