SEATTLE — Jonah Tong received a parting message from Mets brass after Tuesday night’s game: throw strikes.

The right-hander was optioned to Triple-A Syracuse after a rough outing as a bulk reliever, allowing the Mets to add a fresh bullpen arm for Wednesday’s series finale against the Mariners.

In 10 innings over three appearances following his recall, Tong walked seven batters. That included two over 3 ¹/₃ innings in his latest outing, in which he surrendered four earned runs on five hits.

“Go down there, continue to work on some of the things that he needs to work on, especially throwing strikes, competing in the strike zone,” manager Carlos Mendoza said as the Mets avoided the sweep with a 7-1 blowout win over the Mariners. “This is a guy, he’s too talented and obviously we need to see consistency with him throwing strikes and we need him to go down there and develop.”

The Mets recalled reliever Joey Gerber from Syracuse.

Jonah Tong, who struggled in the Mets’ loss on Tuesday night, was sent back to the minors. Getty Images

As for Tong’s rotation spot of sorts — he was pitching behind an opener — Mendoza indicated the built-in off days Thursday and Monday allow the team to leave it vacant the next turn through the rotation.

Kodai Senga threw 91 pitches over five innings in a minor league rehab start for Triple-A Syracuse.

He allowed three earned runs on six hits and two walks with five strikeouts.

The right-hander could potentially return to the Mets next week, but also may be asked to start again in the minor leagues.

Jorge Polanco played first base in a rehab game for Syracuse, but Mendoza said it hadn’t been decided whether the veteran infielder will rejoin the Mets this weekend in San Diego.

Once he rejoins the Mets, the switch-hitting Polanco is expected to serve primarily as a DH.

Jared Young went 2-for-5 with an RBI double, giving him three multi-hit games this season. … The Mets’ three stolen bases matched a season high. Juan Soto, Carson Benge and A.J. Ewing each swiped a base, giving the Mets three players with a stolen base in a game for the first time this season.