The Mets don’t have a confirmed starting pitcher past Monday, when Robert Gsellman -- a recent rotation convert, who is only stretched out long enough to last three or four innings -- will take the mound. Team officials are waiting for injury clarity on Jacob deGrom, Michael Wacha and David Peterson. They’re considering bouncing Steven Matz from the rotation.

At the moment, their starting five is being held together with Scotch tape.

• Box score

It was with that backdrop that de facto No. 2 starter Rick Porcello took the mound on Sunday opposite Zack Wheeler, a stalwart of the Mets’ rotation the past two seasons. Porcello allowed four runs in six innings at Citizens Bank Park, which kept his team in the game. But Wheeler ceded only two runs in seven innings, sending his old team to a 6-2 loss and three-game series sweep in Philadelphia.

“It’s tough, I’m not going to lie to you,” Porcello said. “Guys are coming in and making spot starts or whatever. We’ve had some unfortunate things with guys going down or being sore and things like that, so as far as the momentum of the rotation goes and having those same five go out there and take the ball every day, that’s not happening for us. But it doesn’t mean that we can’t build off one another no matter who’s on the mound.”

As in recent outings, Porcello recovered from a rocky start to settle into a middle-innings groove. Only this time, he caved for an Alec Bohm RBI double and an Andrew McCutchen two-run homer in the sixth, turning a one-run lead into a two-run deficit. The Mets, who made two fielding errors and ran into multiple outs on the bases, never recovered.

“We’ve just got to stay positive,” manager Luis Rojas said. “We’re playing mostly against our own division, so fate is in our hands.”

The Mets’ mistakes on Sunday aided Wheeler, who signed with the Phillies over the winter after six seasons with the Mets. Asked earlier this year about the Mets’ pursuit of him -- or lack thereof -- in free agency, Wheeler replied that “it was basically just crickets.” He added that the silence is “how they roll,” prompting Mets general manager Brodie Van Wagenen to say he was “surprised” and “disappointed” at Wheeler’s comments after the Mets “helped him parlay two good half-seasons over the last five into $118 million.”

Those comments, as well as Wheeler’s long-standing relationship with the Mets, resulted in him having some “extra adrenaline” going into Sunday’s start.

“I’m not trying to prove anybody wrong,” Wheeler said. “Just go out there and just pitch my game and just try to get a win for us. And I was able to do that.”

In truth, the Mets never pursued Wheeler because they had effectively chosen Marcus Stroman over him at the 2019 Trade Deadline. Rather than attempt to sign Wheeler to a contract extension at that time (or at any earlier juncture of Wheeler’s Mets career), the team acquired Stroman from the Blue Jays as a ready-made Wheeler replacement. Because Stroman was under team control for 2020, the Mets knew he could assume Wheeler’s rotation spot when Wheeler left via free agency. Van Wagenen then supplemented the new-look starting five with Porcello and Wacha, inking both to one-year contracts.

It was a cheaper alternative than shelling out $118 million for Wheeler, but one that has yet to work in their favor. Months after Wheeler signed with the Phillies, his former teammate Noah Syndergaard underwent Tommy John surgery. Then Stroman elected not to play due to COVID-19 concerns, leaving the Mets with a perilously thin rotation. Injuries to Wacha and deGrom did additional harm to the group, as did poor performances from Porcello and Matz.

Thus, the Mets find themselves in their current predicament: last place in the NL East (9-14), without a clear idea of who will pitch for them this week. Because they are still within easy striking distance of a playoff spot, the Mets have no reason to panic. But they understand their rotation deficiencies must change if they are to make a run.

“Is it bitter that we just got swept? Absolutely,” third baseman J.D. Davis said. “It’s unacceptable. I hate losing. And everybody in that locker room hates losing, and especially getting swept by the Phillies. It’s unacceptable. But at the same time, there’s positivity in all of us. We know that we can bounce back.”