The Mets rotation has again become a strength.

Coming into Monday’s 12-2 win over the Arizona Diamondbacks, New York’s starters had accumulated a 2.86 ERA in their previous 154.1 innings. Jacob deGrom kept the ball rolling by allowing just one earned run over eight innings last night, so if the Mets can keep this up from a rotation standpoint, they’ll be in good shape.

However, a glaring flaw for this team is how horrendous the bullpen has been.

In its last 22 games coming into Monday, the Mets bullpen is 2-10 with a 6.41 ERA (52 ER/73.0 IP). Overall, the ‘pen has 14 wins, tied for the 11th-most in the Majors and 18 losses, the most in the Majors.

Despite allowing a run on Sunday, Jeurys Familia has overall been a strength for New York, along with the emergence of Robert Gsellman and the return of Anthony Swarzak. Seth Lugo will be a big boost when he returns from the rotation, but he will likely get the ball every fifth day for now until Noah Syndergaard returns from the disabled list.

With only a few guys truly doing well, and that 6.41 ERA over the last few weeks, it’s time for a bit of a shakeup.

On the current 25-man roster, there are three relievers who should be in danger of being demoted: Paul Sewald, Hansel Robles and Chris Beck.

Sewald, who started the year off with a 1.98 ERA over seven appearances in the months of March and April has tailed off precipitously. Last month, he registered a 5.29 ERA (10 ER/17.0 IP) and so far this month has been lit up to the tune of seven runs in six games.

He has also been terrible with runners in scoring position. In 40 plate appearances, batters have 12 hits and four home runs against him, while hitting .353/.400/.764.

In 2017, the right-hander was leaned on heavily by Terry Collins, and the same has been true this year for Mickey Callaway. However, it’s time Sewald takes a trip to Las Vegas, because he isn’t helping here in New York.

Next up is Hansel Robles, who is a more perplexing pitcher. It’s amazing how hot and cold his pitching is. He could go from allowing a home run or walking a batter on four pitches to striking out the next guy on three.

That’s the main issue with Robles. There is no consistency. And more times than not, the Mets get the bad version of him than the good version.

Overall on the year, Hansel is 2-2 with a 4.50 ERA, 86 ERA+, 6.31 FIP and 1.389 WHIP. Apart from Rafael Montero, Robles is the other cat with nine lives on the Mets roster. I’m sure the team sees potential in him, but the results aren’t there and haven’t been in the last two seasons, so it’s time for him to point to the sky in Vegas or elsewhere and not here.

And lastly, we have Chris Beck.

As Mets fans, you might not be too familiar with the team’s newest reliever, who they picked up from the Chicago White Sox off waivers last week. Beck has pitched just one game for New York, but should be on a very short leash.

To be honest, this was a head scratcher of a pickup from the get go. Beck pitched a full season with Chicago last year, and in 57 games, logged a 6.40 ERA and 6.84 FIP.

Prior to being waived by the White Sox this year, he had a 4.18 ERA and 6.01 FIP in 23.2 innings.

Whatever the Mets saw in Beck is questionable, possibly his 95-97 mph fastball, but who knows? Maybe he can turn his fortunes around. Either way, if he has a few disastrous outings, he needs to be out of here.

A fourth name in the Mets pen who has struggled and is worth mentioning is Jerry Blevins.

Blevins, who has been a staple in the Mets bullpen since 2015, is having his roughest season in orange and blue. In 30 games (15.2 innings), he has a 5.17 ERA and a 4.69 FIP.

In the past, Blevins has been tough on lefties, but this year they have teed off against him to the tune of a .342/.405/.500 slash line. He has been better against righties, who are hitting just .130 off him, but still have a high .355 OBP against him.

The main problem with Blevins is that he’s had a hard time controlling and throwing his slider effectively.

I understand Callaway has his hands tied at times with the bullpen he’s been handed, but Blevins should not be used in high leverage situations until he can prove he’s turned a corner.

With RISP this year, batters have hit .400 against him (6-for-15). He has been better this month with a 2.70 ERA, but even still, the Mets should have him pitch when the stakes are low and ease him back into a prominent role when he’s ready.

With all that being said, the Mets have several pitchers in the minors they should consider bringing up to inject some life into the bullpen.

On the 40-man roster alone, there are four pitchers who could be helpful out of the bullpen: Tim Peterson, P.J. Conlon, Tyler Bashlor and Corey Oswalt.

We have seen Peterson, Conlon and Oswalt in the bigs this year, and while the latter two have worked primarily as starters, Conlon could give New York a second lefty and Oswalt could give them a long man and spot starter.

As for Bashlor, he is currently pitching for Double-A Binghamton, where he has a 2.86 ERA in 19 games (22.0 IP) and has a .192 BAA.

Peterson pitched up here and did well in a limited sample size, but was the roster casualty when the team acquired Beck. In three games, he allowed just one run in 4.1 innings.

Conlon too had a cup of coffee with New York earlier this year, then was lost to the Dodgers via a waiver claim, and then was reacquired by New York when LA waived him a day or two later.

He won’t blow guys away with his pitches and doesn’t have the longevity to profile as a starter long term, but he could be effective as a reliever for one or two frames or even as a LOOGY when necessary.

Apart from these guys, there are several other relievers who the team should consider promoting: Drew Smith and Scott Copeland.

Smith, who was acquired by the Mets in the trade that sent Lucas Duda to Tampa Bay last year, is having a solid campaign for Triple-A Las Vegas, pitching to a 2.70 ERA across 33.1 innings.

Perhaps most impressive is that he has allowed just two home runs in his stint with Vegas, who play in the hitter-friendly Pacific Coast League. Smith has always been able to limit the long ball, and has given up just four home runs total in his time as a professional baseball player.

As for Copeland, the right-hander pitched in one game for New York last month before being designated for assignment. Is he an answer long term? Who knows. But he held the Cubs at bay in 1.1 innings when the rest of the bullpen was in shambles, so I’d like to see if he could be a solid piece. If not, he can’t be much worse than what we currently have.

These next few weeks will truly make or break the Mets and will determine if they’re buyers or sellers this year. If they’re still in it next month, acquiring a reliever or two is of utmost importance. Until then, there are several guys in the system that the big club should take a flyer on.