Dickey was 20-6 with a 2.73 ERA last season, capping his rapid rise from the majors' scrap heap to an ace pitcher. He did it by perfecting a way to throw his floater faster than previous knuckleballers, and tossing it with exceptional control.
"It was an extraordinary privilege for us to be part of his career," Alderson said. "The final chapter has not been written."
Dickey joins a stellar Toronto rotation that includes Johnson, Buehrle and returning starters Ricky Romero and Brandon Morrow.
"We clearly are convinced this can be a front-line starter for us," Anthopoulos said. "I don't think he gets the credit or the respect he deserves because of his age, and because of what he does throw. And I understand because it's so rare.
"But there's so much overwhelming data and evidence that points to him continuing to have this success."
Thole gives the Blue Jays a catcher who is familiar with handling Dickey's knuckleball, and Anthopoulos said that relationship was a key to the deal.
"R.A. is too important to our chances to take a chance and have a tryout camp to see if someone can catch him," he said.
Despite a big spot in the rotation to fill minus Dickey, Alderson said the Mets were not giving up on next season.
"We certainly are not punting on 2013," he said.
Alderson called d'Arnaud, who turns 24 in February, the top catching prospect in the minors and predicted he could contribute on the major league level next year. He hit .333 at Triple-A Las Vegas with 16 homers and 52 RBIs before tearing a knee ligament trying to break up a double play in June.
Popular with Mets fans, Dickey perturbed team management when he spoke about his contract situation last week during a club event at Citi Field for children displaced from their schools by Superstorm Sandy.
Dickey said he enjoyed playing for the Mets and added it would be "disappointing" if he went through his option year without a new deal and became a free agent.
"If that's the decision that they make, I feel like it would be unfortunate because it probably is going to mean that I'm not going to be back," Dickey said then. "And that would be sad."
Buck was an All-Star with Toronto in 2010. The 32-year-old hit .192 with 12 homers and 41 RBIs for Miami last season, then was part of the blockbuster trade between the Marlins and Blue Jays.
The 20-year-old Syndergaard went 8-5 with a 2.60 ERA for Class-A Lansing. The 18-year-old Becerra hit .250 with four RBIs in 11 games in the rookie Gulf Coast League.
Thole, 26, hit .234 with one homer and 21 RBIs in 104 games this year. The 29-year-old Nickeas split last season between the Mets and Triple-A Buffalo. He batted .174 with one homer and 13 RBIs for New York.
AP Sports Writers Ronald Blum and Mike Fitzpatrick contributed to this report.