Travis d’Arnaud is closing in on beginning a minor league rehab assignment, the next step in his comeback from a strained right rotator cuff in his shoulder.

Aside from throwing to all the bases, d’Arnaud has checked every box when it comes to completing baseball activities, putting him on track to begin playing in games again.

“I’m excited that everything is coming together, excited to get back on the diamond,” said d’Arnaud, who has been out since April 25.

The Mets have struggled mightily to extract any offensive production from the catching position, which they had expected to be a strength. Taken together, Mets catchers have posted a .558 OPS this season, which ranks dead last in the National League. It is well below the league average OPS of .694.

When healthy last season, d’Arnaud hit .268 with 12 homers and 41 RBIs in 67 games, well above-average production when compared to other catchers in the league. But he was hitting just .196 in just 13 games this season when he was sidelined by the shoulder injury.

Kevin Plawecki, d’Arnaud’s replacement, has hardly fared much better. The former first-round draft pick is hitting .197 with a homer and five RBIs in 24 games since taking over most of the Mets’ catching duties.

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Backup Rene Rivera, a veteran known more for his defensive abilities, is hitting just .148.

Roster moves

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Utility man Eric Campbell was optioned to Triple-A Las Vegas on Tuesday when veteran first baseman James Loney was officially activated. Campbell was hitting .159 in 30 games this season.

The Mets opted to keep recently promoted utility man Ty Kelly on the roster partly because he is a switch hitter, manager Terry Collins said.

“I’d really like to have the switch-hitter sitting on the bench right now with his versatility,” Collins said.

To clear space on the 40-man roster, righthander Jeff Walters was designated for assignment. Walters had a 9.27 ERA in 23 relief appearances at Triple-A Las Vegas.