Brett Baty’s defensive strides have been noteworthy, but Mets officials were looking toward offense in reaching a decision Friday on the team’s immediate plans for third base. 

And that meant sticking with Mark Vientos. 

Baty was optioned to Triple-A Syracuse, giving the Mets the roster flexibility needed to add a backup middle infielder and assuring that Vientos, unless there’s an injury, will be the team’s starting third baseman for at least the next 1 ½ weeks.

Baty must remain at Syracuse for at least 10 days unless he’s the corresponding move for a player placed on the injured list. 

The fact the Mets expected to face four left-handed starting pitchers in six games, beginning with Arizona’s Jordan Montgomery on Friday, played heavily into the decision to demote Baty, according to manager Carlos Mendoza. 

Vientos entered play with a .270/.341/.541 slash line with two homers and four RBIs since his recall from Syracuse on May 15.

He went 3-for-5 with two RBIs on Friday night.

“It was not an easy decision,” Mendoza said before the Mets’ 10-9 win over the Diamondbacks. “But it’s time for [Baty] to go down there and continue to get playing time, continue to get reps, continue to develop and then he will be back here. We told him that.”

Baty’s exit allowed the Mets to select veteran Jose Iglesias from Syracuse as a spare middle infielder.

The Mets were without a backup second baseman/shortstop for the last 2 ½ weeks, after Joey Wendle was designated for assignment.

Iglesias was in Friday’s starting lineup as the second baseman, with Jeff McNeil on the bench. 

Baty, after a fast start, has sputtered offensively.

Overall he owns a .225/.304/.325 slash line with four homers and 16 RBIs.

Baty’s average exit velocity of 86.3 mph ranks only in MLB’s 14th percentile. 

“I think Brett has done a great job at focusing on what we have asked him to focus on,” Mets president of baseball operations David Stearns told The Post. “We asked him to improve defensively and he’s improved quite a bit defensively. We’re facing a bunch of lefties here coming up and it made sense to get him consistent at-bats and get that going again.” 

Baty has played just 32 games at Triple-A in his career, but has dominated at the level. Mendoza downplayed the idea that Baty might be putting extra pressure on himself trying to impress a new Mets regime. 

“I think it’s part of the development,” Mendoza said. “He’s trying to perform at the highest level and there’s always pressure.” 

Iglesias (1-for-4) also can play third base for the Mets as needed, according to Mendoza. But the job will belong primarily to Vientos for the first time in his MLB career. Just the fact the Mets were comfortable enough to choose that course speaks to Vientos’ steady improvement at the position.

Just the fact the Mets were comfortable enough to choose that course speaks to Vientos’ steady improvement at the position. 

“He’s done a very solid job over there,” Stearns said. 

Vientos said he is pleased with his progress, but is disappointed his close friend Baty has departed. 

“I’m rooting for him,” Vientos said. “I know he’s going to go down there and work and get better and he’s going to be back here soon for sure.” 

Vientos was asked about his own comfort level at third base — he also subbed at first base for Pete Alonso for one start this week. 

“I have been working hard every day and the hard work is showing off,” Vientos said.