ST. LOUIS — Though it might be too little too late, the Mets expect several of their banged-up key players to ramp up their efforts to come off the disabled list.

According to pitching coach Dan Warthen, Noah Syndergaard (torn right lat) is set to begin throwing in less than two weeks. Warthen said Matt Harvey (stress injury, right shoulder) will begin his own throwing program when the Mets resume play after the All-Star break.

Harvey went on the disabled list on June 15 after a start in which his fastball barely cracked 90 mph. He is 4-3 with a 5.25 ERA in his first season after surgery to correct thoracic outlet syndrome.

Warthen said Sunday that the procedure left Harvey with weakness in the muscles behind his throwing shoulder, which led to problems as he tried to pitch during the first half. Only after Harvey went on the disabled list did doctors discover that the muscles behind his right shoulder were roughly half the size of those on his left, Warthen said.

“It totally atrophied,” he said. “He didn’t have the strength to maintain, so his bullpens wouldn’t be good. The first inning would be good and then all of a sudden that thing wouldn’t work, it wouldn’t fire. That’s been the whole thing. We’ve been building that back up the whole time.”

Closer Jeurys Familia (blood clot, right arm) is set to begin a throwing program at the All-Star break.

It remains unclear when the Mets’ injured arms will return to action.

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Warthen raised the possibility of using Syndergaard in relief once healthy. He said that discussion will revolve around the Mets’ needs and whether they are in contention. They enter the All-Star break with a 39-47 record.

“If we decide we want to go get Syndergaard back earlier but use him as a one-inning guy, we’ll all talk about that,” Warthen said.

Robert Gsellman (strained left hamstring) still must make more progress before beginning a throwing program.

“He’s again doing the rehab stuff and making sure his leg’s OK,” manager Terry Collins said. “But we can’t do too much throwing-wise until we know his legs are going to be able to handle it.”

Second baseman Neil Walker traveled to Florida after Saturday’s game in hopes of increasing his workload ahead of a minor-league rehab assignment.

Said Collins: “Hopefully, in a short period of time, he’ll be back in the mix.”