WEST PALM BEACH, Fla. -- A day after learning that fourth starter José Quintana had suffered a stress fracture in one of his ribs, Mets manager Buck Showalter on Tuesday was still “hoping for good news” regarding the left-hander’s long-term prognosis. Quintana’s original flight back to New York was canceled, forcing him to reschedule some additional testing.

The Mets should have more information on Quintana in the coming days. In the interim, they have already begun espousing the next-man-up mantra that all teams look to follow.

“One of our strengths last year, which was instrumental in winning the games we did, was the depth,” Showalter said. “That’s something that Billy and the front office have been very adamant about. We’re in a position to do that, but it does take it one more notch down on the depth list.”

Should Quintana miss time in April or beyond (as many around the team suspect), David Peterson would be the most obvious candidate to take his rotation spot. Although Peterson is dealing with an injury of his own after taking a comebacker off his left foot in Saturday’s game against the Marlins, he did not suffer any broken bones and should return to the mound in quick order. After making 19 starts in the Majors last season, Peterson entered camp knowing he had an excellent chance to contribute to the rotation again.

“There’s been a lot of attention as to the average age of our starting rotation,” Peterson said. “The likelihood of those five guys making 30 starts each is highly unlikely. … So I think it was just kind of come in and do my work and help contribute how I can.”

Peterson pointed to last year, when neither Jacob deGrom nor Max Scherzer was physically ready to pitch on Opening Day, forcing the Mets to shift Tylor Megill into that role. Megill, who threw 2 1/3 scoreless innings in a 5-5 tie with the Astros on Tuesday, is another candidate to replace Quintana. So are veterans Elieser Hernandez and Joey Lucchesi.

This could develop into one of the few real competitions in Mets camp, where most starting positions were sewn up long before the start of Spring Training.

“Me and Peterson, we’re ready for whatever gets thrown at us,” Megill said. “Whoever’s name gets called, we’re available to help the team. That’s all we want to do is help the team win.”

Ruf debuts
Darin Ruf made his Grapefruit League debut Tuesday at The Ballpark of the Palm Beaches, finishing 0-for-3 with two strikeouts. Ruf missed time early in camp after receiving a cortisone shot in his arthritic right wrist.

The right-handed half of a DH platoon with Daniel Vogelbach, Ruf hopes to rebound from a second half that saw him slash .152/.216/.197 following a midseason trade from the Giants to the Mets. If Ruf falters, outfielder Tommy Pham could soak up some of his DH reps. Eventually, prospects Francisco Álvarez and Mark Vientos may threaten to do the same.

Only four players in big league camp have yet to debut:

• Infielder Danny Mendick, who spent last offseason rehabbing a torn ACL and is due to play Wednesday in an exhibition against Team Nicaragua
• Outfielder Starling Marte, who underwent groin surgery in November and is scheduled to play Friday
• Outfielder Brandon Nimmo, who is healthy but progressing slowly by design, with an expectation of debuting by the end of this week
• Reliever David Robertson, who threw live BP on Tuesday and should also debut soon

Bullpen competition
Rule 5 Draft pick Zach Greene endured his worst Grapefruit League outing on Tuesday, when he allowed three runs in the bottom of the ninth to spoil a potential Mets win. Greene has allowed five earned runs over his last two appearances. Overall this spring, he holds a 12.27 ERA with five walks and three strikeouts.

Greene entered camp with a chance to lock down a bullpen spot in part because of his Rule 5 status, which requires the Mets to return him to the Yankees for a small fee if he does not make the team. But more poor performances could hinder Greene's chances, with a host of other candidates present, including Stephen Nogosek, Tommy Hunter, John Curtiss and Sam Coonrod. The Mets have three open spots in their bullpen.

"There's plenty of time for him," Showalter said of Greene. "He already has shown us some good things. Tonight, statistically it might not look good, but there were a couple of borderline calls. He had strike three. I can see why we thought well of him, and he'll continue to get opportunities to present himself."