It wasn't long ago that Blackwood was considered the next hot, young netminder. He has the pedigree as a high second-round pick, and his first 70 NHL games were excellent from 2018 to 2020. With save percentages of .918 in 18-19 and .915 in 19-20.
Blackwood struggled with a heel injury last season and his numbers have been poor for two seasons now. His save percentage was an ugly .892 in 25 games with a record of 9-10-4. The sense is the Devils, can't afford another season with shoddy goaltending, and have lost faith in Blackwood.
Veteran goalie Petr Mrazek is signed for two more seasons at a cap hit of 3.8 million per year. $6.6 million per season for your goalie tandem would be great especially for a team as a tight against the cap as the Leafs. It would be extremely risky to go into next season hoping both bounce back from injury riddled seasons.