PORT ST. LUCIE — Nerves were taking their toll on Fernando Salas.

As a first-time free agent, the righty reliever wasn’t quite sure what to expect during the offseason, but arriving in late January without a job was eye-opening to say the least.

Salas ultimately received a one-year deal worth $3 million for a return to the Mets, who hadn’t been aggressive in pursuing him for most of the winter.

“When my agent told me I had a shot to go back to the Mets I was happy, because this is a great organization and really good fans,” Salas said Monday.

The Mets were patient in an effort to wait out the market, allowing them to re-sign lefty Jerry Blevins as a relative bargain for one year (with an option) for $6.5 million.

Salas was near the top of the Mets’ list for a righty in the setup role. According to an industry source, the team considered veteran Sergio Romo, but had concerns about the mileage on his right arm and believed the 31-year-old Salas had a higher upside.

Salas arrived in a waiver deal from the Angels last season and thrived over the final month, emerging as the primary seventh-inning option. In 17 appearances for the Mets, he was 0-1 with a 2.08 ERA and 0.635 WHIP.

With Jeurys Familia facing a likely suspension to begin the season after his offseason arrest on domestic violence charges, manager Terry Collins is prepared to slide Addison Reed into the closer’s role. The trickle-down is Salas likely will begin the season as the Mets’ primary eighth-inning option.

“As of today he would be that guy, because he has done it before and he’s been successful at it,” Collins said. “As we have seen in the last couple of years, the big inning is the seventh inning. How can we piecemeal that to get to the eighth inning? How can we get to Addison and then Jeurys in the last couple of innings?

“We’ve got to make sure early in the year, no matter how long Jeurys may be gone, we’ve got to find those answers — especially early in the year when guys aren’t going seven innings. Your starting pitching is going five. You have got to get through six and seven.”

Salas says he is ready for any challenge the manager gives him.

“The most important thing for me is to stay healthy,” said Salas, who has topped 70 appearances in each of the last two seasons. “If I can stay healthy, I can help the team. I feel happy for this opportunity.”