MLB

Mets, Blue Jays now discussing 7-player trade involving R.A. Dickey

What started as trading R.A. Dickey for multiple prospects had become potentially something bigger yesterday.

As first reported by The Post, the Mets were close to a seven-player deal with the Blue Jays, according to sources, that would send the NL Cy Young Award winner to Toronto for stud catching prospect Travis d’Arnaud. In addition, the Mets would send catcher Josh Thole and a non-elite prospect to the Blue Jays for their top pitching prospect, Noah Syndergaard, catcher John Buck and another non-elite prospect.

Not a possibility for the Mets, according to an industry source, was receiving highly regarded outfielder Anthony Gose.

The remaining hurdle yesterday, according to sources, was the Blue Jays receiving assurance Dickey, who will make $5 million next season in the final year of his contract, would sign a two-year extension.

The 23-year-old d’Arnaud remains the key to the deal for the Mets. He is regarded as the top catching prospect in baseball and the best overall hitter in the Blue Jays’ farm system.

In 67 games at Triple-A Las Vegas last season, d’Arnaud hit .333 with 16 homers and 52 RBIs before a knee injury ended his season in late June.

”He’s a solid defensive catcher with some power,” an NL talent evaluator said. “You can throw those Vegas numbers completely out of the book [because of the altitude]. But he’s going to be an upgrade for sure.”

The former first-round draft pick was sent to the Blue Jays as part of the deal that brought Roy Halladay to the Phillies in 2009. Before last season, d’Arnaud was rated by Baseball America as the 17th-best prospect in baseball.

“It would be a good get for the New York Mets,” an AL scout said.

But the scout warned the Mets should at least have some concern about the posterior collateral ligament injury that sidelined d’Arnaud for much of last season.

“It’s not great for catchers, but nowadays they do a super job rehabbing these injuries and he’s young,” the scout said. “I like the bat along with the defense. I could see him as maybe a catcher and first-base combo.”

The 20-year-old Syndergaard also would be a potential key component to the trade. The righty went 8-5 with a 2.60 ERA for Single-A Lansing last season with 122 strikeouts in 103 ²/₃ innings.

Syndergaard was the 38th overall pick in the 2010 draft and boasts a fastball in the 95-mph range. He was rated by Baseball America as the Blue Jays’ No. 3 prospect after last season.

Buck arrived to the Blue Jays in last month’s mega-trade from the Marlins and would offset the loss of Thole, whom Toronto is believed to want because of his experience handling Dickey’s knuckleball.

Last week, Dickey indicated he was not pleased with the Mets’ most recent contract offer — a two-year extension worth $20 million, according to sources — and wouldn’t be surprised if he were traded. Dickey’s asking price from the Mets was $26 million over two years, beginning in 2014.

Dickey, who went 20-6 with a 2.73 ERA last season, would give the Blue Jays a missing piece to their rotation, as they attempt to go for broke in the AL East next season. The Blue Jays already have added Jose Reyes, Josh Johnson, Mark Buehrle, Emilio Bonifacio and Buck in a trade with the Marlins and signed outfielder Melky Cabrera.

mpuma@nypost.com