PORT ST. LUCIE, Fla. -- The United States government has delayed Jenrry Mejia's attempts to obtain a visa to enter the country, pending an investigation into his age and identity.

General manager Sandy Alderson said he believes the review of Mejia's documents is random, though such investigations are rare for international players who have already spent multiple summers in the States. Major League Baseball is conducting the identity review for the U.S. consulate, and the Mets informed the league that they consider it a priority.

Still, the club has no clear idea of how long it may take.

"It was unanticipated by the player, by us, by Major League Baseball for that matter," Alderson said. "It's very unusual for a Latin player who has been to the United States on multiple occasions and has been on a Major League roster for several years to be investigated. But as I said, we don't believe there's any specific reason for it. We think it was done on a random basis."

Mejia, who is officially listed as 22 years old, has played professionally in the United States since 2008. He is working out at the Mets' training facility in the Dominican Republic in an effort to remain on pace with his peers in Florida.

"I'm hoping that the work he's able to get there will not leave him too far behind when he actually gets here," Alderson said.

Though he will likely open this season at Triple-A Las Vegas, Mejia is a fringe candidate for the Mets' Opening Day bullpen. The length of his travel delay could affect that competition.

Alderson: Fifth year for Bourn was stumbling block

PORT ST. LUCIE, Fla. -- Even if the Mets had received a positive ruling on their Draft pick concerns in their pursuit of outfielder Michael Bourn, they may not have signed him to a free-agent contract. General manager Sandy Alderson said Wednesday that Bourn's desire for a fifth-year vesting option was critical to New York's decision to bow out of negotiations.

"There were two issues," Alderson said. "One was the fifth-year vest, which we viewed as a fifth year in the contract at the levels we were talking about. We weren't prepared to go to five years, and they had known that for some time. The vest was a big issue for us."

The Mets previously made their stance with regard to the 11th overall pick in the First-Year Player Draft well known. If the league ruled that the Mets would have to forfeit their first-round pick to sign Bourn, they would not have proceeded.

But it never reached that point because neither the Mets nor Bourn caved in negotiations. Bourn sought a fifth-year option, which he ultimately received in his four-year, $48 million deal with the Indians. Alderson indicated he was unwilling to add that clause, even if it meant losing out on a premium free agent.

"There's some disappointment, obviously," Alderson said. "We made a strong effort to try to sign him and weren't able to do it, which is unfortunate. But, nonetheless, we move on."

Per Mets' wishes, Santana doubtful for Classic

PORT ST. LUCIE, Fla. -- General manager Sandy Alderson again hinted that Johan Santana is unlikely to pitch in the World Baseball Classic, despite Santana's desire to represent his native Venezuela.

"It's a complicated situation, just because of his injury and the fact that he did not pitch at the end of last season," Alderson said. "Ultimately, he needs our permission to play, and what we're going to do is take a look at it over the next few days."

Because Santana finished last season on the disabled list, the World Baseball Classic would need to insure the $31 million remaining on his contract for him to gain eligibility. That in itself is unlikely, and even if it comes to pass, the Mets could still ask Santana not to play. The left-hander has said that he would respect those wishes.

"We're very concerned that he'd be ready to go and healthy for us," Alderson said. "There are reasons why players in his situation at the end of a previous season typically don't play in the WBC. So we'll have to take a hard look at it."

Worth noting

• The Mets have added two Citi Field Fireworks Nights to their promotional calendar on May 24 (following a 7:10 p.m. ET game against the Braves) and July 3 (7:10 p.m. against the D-backs), the team announced Wednesday.

• The club also announced that All-Star Six Packs are on sale now at mets.com. Each pack includes a guaranteed ticket to Opening Day or a Subway Series game, in addition to five other regular-season games and Major League Baseball's All-Star FanFest in July. The Mets plan to announce additional promotional dates in the weeks ahead.