PORT ST. LUCIE — December was a star-studded month for the Mets, one in which the rotation got rebuilt and the team re-signed the best center fielder on the free-agent market.
Justin Verlander, Kodai Senga, Jose Quintana and Brandon Nimmo all arrived (or in Nimmo’s case, returned).
Way down on the list of transactions was the addition of David Robertson on a one-year contract worth $10 million. A month later, Adam Ottavino returned on a two-year deal worth $14.5 million.
Those less-trumpeted signings now loom among the Mets’ largest, at least if the team plans to compete for a World Series title this season.
Edwin Diaz’s likely season-ending right knee injury, sustained in the on-field jubilation Wednesday night as the All-Star closer celebrated Puerto Rico’s victory over the Dominican Republic in the World Baseball Classic, has changed the Mets’ entire bullpen dynamic.

Robertson owns plenty of big-game closing experience and likely will receive the lion’s share of the duties in Diaz’s spot. But Ottavino can slide into that spot as needed, giving the Mets a workable dynamic.
Robertson is the more intriguing choice based on a resume that includes plenty of winning teams and high-pressure situations with the Yankees, Cubs and Phillies. And there is this: The right-hander has been as effective against lefties as against righties over the years. Last season, that meant holding right-handed hitters to a .629 OPS. Left-handed hitters owned an even paltrier .550 OPS against him.
Ottavino is more the classic late-inning flamethrower, who, like Robertson, knows plenty about performing on a big stage, following stints with the Yankees and Red Sox.
Diaz is close to irreplaceable, but Robertson and Ottavino can perhaps give the Mets a chance in that closer’s role.
The larger issue for the Mets will be trying to figure out who replaces Robertson/Ottavino in the setup role.
The Quintana replacement plan

Tylor Megill was thrust into the Mets’ Grapefruit League game against the Marlins earlier this week — sending Max Scherzer to a back field to get in his work — because it was deemed important he stretch out against major league hitters.
The Mets are going to need Megill one way or another this season, but Jose Quintana’s impending bone graft to cover a benign lesion on his fractured fifth rib on his left side has left the team with a long-term vacancy in the rotation.
By general manager Billy Eppler’s timetable, Quintana’s absence will last beyond July 1.
As much as the Mets like David Peterson for his solid work last season filling in, there is substantial thought about giving the job to Megill, even at the expense of having a lefty in the rotation.
Remember, the Mets were to employ an all right-handed rotation last season of Scherzer, Jacob deGrom, Chris Bassitt, Taijuan Walker and Carlos Carrasco. Then deGrom got injured in spring training, and the job went to Megill. But Megill began with his own injury troubles in May, leading to Peterson’s steady involvement.

Megill probably has the higher ceiling among the two pitchers based on his filthier stuff, even as he looks to preserve bullets by not throwing every pitch as if it’s his last.
That isn’t to minimize what Peterson meant to the club last year, when he started 19 games and pitched to a 3.86 ERA in that role. That is certainly acceptable for a back-of-the-rotation starter.
But Mets officials also have a snapshot of Megill’s work that is hard to ignore: a five-game stretch in April in which he pitched to a 1.93 ERA and appeared worthy of holding deGrom’s spot in the rotation.
If the Mets believe Megill is all the way back from the shoulder impingement that sidelined him after a lat strain, it’s probably worth exploring whether he can pick up where he was early last season.
Patience isn’t always a virtue
After the Mets announced Quintana would be lost for at least half the season, Buck Showalter commented that the left-hander’s return would be like a trade deadline acquisition for the Mets.
Predictably, that created a stir on social media.

Mets fans, in particular, have grown weary of such talk — a throwback to the previous ownership regime, which rationalized not taking on a big contract at the trade deadline because Player X would be returning from the injured list to provide that same boost.
But this is a new era under Steve Cohen, so it probably behooves fans to view Showalter’s comments as just trying to put a positive spin on a bad situation. Ideally, Quintana will return and contribute during the season’s second half.
The past two seasons, the Mets have received mixed results from their “trade deadline acquisitions” that were returning from injuries.
Last year, deGrom’s season debut occurred on Aug. 2 in Washington. The right-hander started 11 games, and went 5-4 with a 3.08 ERA with 102 strikeouts in 64 ⅓ innings. The ace’s return certainly provided a boost to the rotation.
In 2021, Carrasco debuted for the Mets on July 30 — he had been sidelined since spring training because of a torn hamstring — and went 1-5 with a 6.04 ERA over 12 starts. After the season he had a bone fragment removed from his right elbow.
It wasn’t much of a “trade deadline acquisition” for a team that unraveled over the final two months of the season.
Max-ing out the WBC
Scherzer raised the idea of playing the WBC during the season when asked this week about the event’s timing. Scherzer is among the pitchers not participating out of fear of injury from ramping up too quickly in spring training.

“Would there be a format where if the WBC was during the season, I think you would get more pitcher participation,” Scherzer said. “And more importantly, I think it would be more exciting for the fans because you would actually have starters built up. You wouldn’t have guys on pitch counts. You would actually have real guys going out and it would be a real game.”
An idea: Skip holding an All-Star Game every fourth season and play a condensed version of the WBC over a week. That is, take a four-day All-Star break and turn it into eight, allowing for a smaller tournament that includes better pitchers.
Adam Wainwright has enjoyed a fine career, but the fact he was the Game 1 starter for Team USA in the tournament — and not a Scherzer, Justin Verlander or Gerrit Cole — only underscores the event’s shortcomings.
“I’m not ready to step into a quasi-playoff game right now, physically,” Scherzer said. “I feel like if I do that, I’m rolling the dice with my arm. If I go out there and try to do too much early in spring, it really could affect me throughout the season.”
Francisco Alvarez’s time is coming

Francisco Alvarez is receiving high marks for his work behind the plate this spring.
It still would be surprising if the 21-year-old is placed on the Opening Day roster — the Mets have Omar Narvaez and Tomas Nido — but expect to see Alvarez at some point over the summer.
“He’s got a lot of aptitude and he puts a lot of effort into getting better,” catching instructor Glenn Sherlock said. “He’s always looking for feedback and looking at video. He’s a very conscientious kid.”