Lucas Duda #21 of the New York Mets runs the...

Lucas Duda #21 of the New York Mets runs the bases after his first-inning home run against the Atlanta Braves at Citi Field on Monday, May 2, 2016. Credit: Jim McIsaac

The loss of Lucas Duda to a stress fracture in his back, the same injury that once felled David Wright for nine weeks, was a troubling development for the Mets on Monday.

One minute, they’re sweating Matt Harvey’s inexplicable slide. The next, it’s saying bye-bye to the only reliable first baseman in the higher rungs of the organization, along with his 30-homer potential, until possibly the All-Star break or even beyond.

Terry Collins immediately suggested an all-hands-on-deck approach to subbing for Duda, reeling off a list of names, as if the sole job requirement was two hands and the ability to put a first baseman’s mitt on one of them. If only it were that easy.

Duda has his detractors, and his inconsistency can be maddening. But he’s Keith Hernandez compared to the Mets’ in-house alternatives, because, really, there aren’t any.

“We’re not going to be able to replace Lucas Duda internally,” assistant general manager John Ricco said. “It’s not like we have another Lucas Duda in the organization.”

Within minutes of Monday’s Duda announcement, team officials were talking about going outside for help, from stopgap solutions to more versatile pieces.

The Padres’ James Loney, hitting .336 for Triple-A El Paso, would bring a solid glove. Kelly Johnson, now with the woeful Braves, certainly would be available for a repeat run. The Brewers might be headed for a yard sale that could put Jonathan Lucroy, a catcher/first baseman, on the market. But because Duda is expected back at some point, they can’t just give away his spot.

In a perfect world, we’d like to see Michael Conforto get some serious reps there, which would allow the Mets to use a far superior defensive outfield with Juan Lagares in center and Yoenis Cespedes in left. Or for Wright to start his inevitable transition across the diamond.

Collins floated both scenarios before last night’s series opener in D.C., but don’t hold your breath. The Mets are leery of messing with Conforto, and he didn’t sound thrilled about trying a position he’s never played, aside from occasionally practicing there at Oregon State.

“All I can tell you is that I’ll do whatever I can to make sure that I’m as ready as possible if that does happen,” Conforto said.

Preparing Conforto to play first base feels more like something that should be put on the Port St. Lucie agenda next February. For all the power Conforto has been providing, with his own 30-homer pace, what’s the point if he gives those runs back while learning a new position?

Wright’s a different story. He’s a 13-year vet, at the other corner infield spot, with a deteriorating arm that needs to be relocated. The complication here is Wright’s back issue, which isn’t likely to respond very well to the extra work.

Also, moving Wright wouldn’t really add much. All it would mean is that Wilmer Flores or Eric Campbell would wind up at third base rather than first.

Collins broached the subject with the Mets’ captain on Sunday. “I’m sure it would be a little weird,” Wright said. “Maybe I can just talk to Keith [Hernandez] for a couple of minutes and learn that way.”

The Mets don’t have the time midseason for either Conforto or Wright to enroll in Mex U. But they should pack that away for next February. For now, the Mets will ride Campbell, and presumably Flores once he’s ready to come off the DL, maybe as early as Friday. Of course, Flores was hitting .180 (9-for-50) with a .535 OPS before getting hurt, and that’s not befitting of a first baseman for the NL champs.

“We’re not in a position right now to just test guys,” Collins said. “We’re supposed to win.”

Without Duda, that just got more difficult.

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