Dubas said he had an idea by Thursday that the forward would be leaving as an unrestricted free agent despite efforts to re-sign him.
"So at that point I think it was fairly clear to us internally, based on the discussions and where they had been or even the feeling on it, that he was going to be on the move," Dubas said. "You know, we had done what we could to try to make it work, and unfortunately we couldn't.
"Everyone knows how we feel about Zach here, and even though it won't be here, we are happy for him."
Dubas' comments came a day after Hyman's agent, Todd Reynolds, told the Toronto Sun, "Zach will be signing elsewhere. He won't be returning to Toronto."
The report said Hyman, who visited the Edmonton Oilers this week, has a deal in place with the Oilers worth $5.1 million to $5.5 million per season, which he can sign July 28.
"I've only heard that Todd made comments," Dubas said. "I actually haven't read the exact comments that were made. But if he announced that Zach was moving on, then that's what we expect."
Hyman scored 33 points (18 goals, 15 assists) this season.
If the Maple Leafs agree to a trade for Hyman before July 28, he would be allowed to sign a maximum eight-year contract before being traded. If not, and he becomes a free agent, he can sign a contract up to seven years with any other NHL team.
"I know that there's a narrative that we should just get something [for Hyman in a trade], but you're saving a team significant dollars on the [NHL] salary cap (with the eighth year)," Dubas said. "That comes with a cost, and we're not going to bend on that."
Selected by the Florida Panthers in the third round (No. 123) of the 2010 NHL Draft, Hyman did not sign with them and was traded to Toronto on June 19, 2015. He has scored 185 points (86 goals, 99 assists) in 345 regular-season games and 13 points (five goals, eight assists) in 32 Stanley Cup Playoff games.
