Five questions facing the Mets in the second half as they return to Citi Field on Friday 10 1⁄2 games back of the second wild-card spot:

1. What can the Mets bring back for their trade pieces?

Barring a surge to start the second half, the Mets will be looking to sell off veterans on expiring contracts. And as usual, bullpen help will be a sought-after commodity at the trade deadline. Righthander Addison Reed (2.53 ERA, 15 saves) is most likely to bring back a solid return, though in what’s expected to be a buyer’s market, that could be a mid-tier prospect. Jay Bruce, Lucas Duda, Curtis Granderson, Asdrubal Cabrera and Neil Walker (once he’s off the DL) also could be on the move.

2. When will the Mets promote Amed Rosario?

The moment Rosario arrives in Queens, he easily would become the best defensive player on the roster, and his presence would shore up what has been a porous defense up the middle. But despite his impressive numbers in Triple-A Las Vegas (.327/.365/.474), the Mets insist he needs more seasoning. Team officials have been wary about putting pressure on him to be the savior of a season that has gone sideways. But the 21-year-old will get the call eventually — perhaps after the trade deadline — a big step as the Mets begin planning for 2018.

3. Will — or should — Noah Syndergaard, Matt Harvey and Jeurys Familia make it back?

The Mets’ chances of bouncing back in 2018 will be shaped by whether their arms can prove they are past the injuries that wrecked the 2017 season. In Syndergaard (torn lat), the Mets lost their staff ace and one of the top starters in baseball. In Familia (blood clot), they lost a closer and one of the best relievers in baseball. Harvey’s road back from thoracic outlet syndrome has proved complicated. Of course, if the Mets fall totally out of contention, it would be wise to be conservative with all three arms.

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4. Can Michael Conforto put together a full season?

Conforto emerged as one of the few highlights of the first half. Initially slated to begin the season in the minor leagues, injuries opened a path for Conforto to make the roster, crack the starting lineup and then represent the Mets at the All-Star Game. Through the season’s first two months, Conforto was hitting .316 with 13 homers and 34 RBIs. Since then? Conforto is hitting .209 with just one homer and seven RBIs. Last year, Conforto struggled to pull himself out of a slide following a fast start. If he is to continue his growth as a player, he can’t afford a repeat this season.

5. Can anything be done to better manage Yoenis Cespedes’ recurring leg issues?

This offseason, the Mets signed Cespedes to a four-year, $110 million contract, locking up one of baseball’s most dynamic players. But he can’t be that player if he can’t stay on the field. From more attention paid to hydration, to a revamped pregame stretching routine, the Mets have taken measures in hopes of sidestepping the type of hamstring and quad problems that limited Cespedes to 42 games in the first half. Given the team’s long-term commitment to Cespedes, it’s an issue that will be relevant far beyond just this season.