Prior to Friday’s game at Citi Field, general manager Billy Eppler said infield prospect Mark Vientos was “definitely on our radar” and added he dispatched his special assistant, Carlos Beltran, to Syracuse to watch Vientos and others on the Triple-A roster to evaluate their readiness to play at the major league level.

And that was before the Mets went on to lose yet another series to a bad team, the Rockies, with two more underwhelming showings from the offense.

According to a National League scout who saw Vientos play this weekend, including his 2-for-3 performance with a double and a homer on Sunday, the 23-year-old could help the lineup, but wouldn’t be able to fix the roster’s problems.

“Everyone knows he can hit,’’ the scout said. “But it’s not like you can just get him up there and solve everything. They’ve got other holes to fill.’’

The scout also noted that Vientos had an 0-for-11 spell last week.

His other point remains true, as the lineup is underperforming as a whole, not just in a spot or two that Vientos, or perhaps Ronny Mauricio, would be able to solve.

Starling Marte is in the midst of an ugly slump that could result in being moved down to the bottom of the order after getting an off day on Sunday followed by the team being off Monday.

The outfielder is in a 10-for-64 slump with no extra-base hits and 16 strikeouts during that stretch.

And as much as Brett Baty has played himself into a regular spot at third base, Eduardo Escobar has played himself out of it.

Even Pete Alonso is struggling, going 7-for-50 with one homer and 15 strikeouts in his last 14 games.

With Alonso at first base and Baty at third, Vientos’ two defensive positions are taken.

The Mets are still looking to get more out of Daniel Vogelbach as their left-handed DH.

He hit just his second homer of the year on Sunday and also made a brutal baserunning mistake.

Vogelbach’s lack of power has hurt the Mets, as well.

“Power comes in bunches,’’ Vogelbach said. “I want to hit more homers and I know I’ll hit more homers, but if you told me at this point in the season, my OPS would be over .800, I’d take it,’’ said Vogelbach, whose OPS is .809. “My job is to hit right-handed pitching and I think I’ve done a pretty good job of that this year.”

Eppler noted on Friday that part of the calculus in bringing up prospects is how much they’d be able to contribute to the major league roster.

With that in mind, Vientos could be limited to a part-time DH role, where the right-handed hitting Mark Canha and Tommy Pham have so far mostly disappointed.

The organization’s attempt to make Mauricio a second baseman has also continued, with 11 of his last 13 starts coming at second base.

He’s coming off a recent three-game stretch in which he went 8-for-13 with two doubles and a triple.